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SANITAKY AND APPLIED CHEMISTEY 



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THE MACMILLAN COMPANY 

NEW YORK • BOSTON • CHICAGO . DALLAS 
ATLANTA • SAN FRANCISCO 

MACMILLAN & CO., Limited 

LONDON • BOMBAY • CALCUTTA 
MELBOURNE 

THE MACMILLAN CO. OF CANADA, Ltd. 

TORONTO 



A TEXT-BOOK OF 

SANITARY AND APPLIED 

CHEMISTRY 

OR 

THE CHEMISTRY OF WATER, 
AIR, AND FOOD 



BY 
E. H. S. BAILEY, Ph.D. 

V 
PROFESSOR OF CHEMISTRY, UNIVERSITY OF KANSAS 



FOURTH EDITION REVISED 



THE MACMILLAN COMPANY 
1917 

All rights reserved 






Copteight, 1906, 1913, AWD 1917, 
By THE MACMILLAN COMPANY. 



Set up and electrotyped. Published July, 1906. Reprinted 
February, 1908; January, 1910; February, 1911; July, 1912; 
January, 1913. 

Revised edition, published December, 1913. Reprinted June, 
December, 1914. 

Fourth edition, revised, May, 1917. 



MAY 17 1917 



J. S. Cushing Co. — Berwick & Smith Go. 
Norwood, Mass., U.S.A. 



Oa A 460878 

%t ■ / - 



PREFACE TO FIRST EDITION 

The object of this work is to furnish a textbook upon 
applied chemistry that is suitable for use by those students 
who have had a course in general chemistry, such as is 
usually completed in a good high school or in the earlier 
years of a college course. The particular phase of applied 
chemistry treated is that which pertains to the daily life 
of the household, but the subjects considered do not by any 
means cover the whole field of what might be called chem- 
istry applied to daily life, but only the most important 
topics. 

Although primarily intended for use as a textbook, 
much scattered material is here collected from Govern- 
ment Reports and elsewhere, so that it is believed the 
book will prove valuable for general information and ref- 
erence. The difficulty of condensing, without sacrificing 
something in clearness, is thoroughly recognized. 

Some simple reactions in general and organic chemistry 
have, it is true, been introduced, but it is believed that they 
are of a kind to be readily understood by students, with a 
little explanation from the instructor. It would be well to 
supplement the text by lectures on the topics studied and 
also to give time for discussions. 

The author believes that a practical method for teaching 
the subject, if a sufficient number of books of reference are 
at hand, is to outline topically the subject to be studied 
and require a preparation on those topics from the student. 

It has been the intention of the author to introduce 
enough facts to render the subject intelligible and readily 



VI PREFACE TO FIRST EDITION 

comprehended, and not to burden the pages with details 
which belong properly to a more voluminous treatise on 
the subject. 

One of the most important features of the book is the 
introduction of experiments, which are distributed 
throughout the text and which it is believed will very 
materially aid the instructor who may have occasion to 
direct the work of the students. These experiments are 
suggested by several years of experience with classes in 
Sanitary and Applied Chemistry, and they are of such a 
character as can be performed in any chemical laboratory 
and with a moderate amount of inexpensive apparatus. 
More difficult experiments, which would involve a knowl- 
edge of quantitative analysis, have been purposely omitted. 
The instructor can add more experiments, if sufficient 
apparatus is at hand and the time allotted to the course 
will permit. 

The first part of the book is devoted to water, air, heat- 
ing, lighting, and ventilation, — to those practical prob- 
lems with which we come in contact every day ; and the 
second part is occupied with a discussion of foods and 
beverages. In the latter section, although many adul- 
terants are pointed out and the simpler tests for them are 
given in the experiments, no attempt is made to do the 
work, which properly belongs to the trained microscopist 
or analytic chemist. 

For many valuable suggestions, which were made while 
the book was going through the press, and for assistance in 
reading proof, the author is especially indebted to Professor 
J. T. Willard, Dr. James Naismith, Professor Isabel Bevier, 
Professor M. A. Barber, Dr. H. P. Cady, Dr. W. D. Bige- 
low, Professor W. C. Hoad, and Mrs. A. T. Bailey. 



PREFACE TO THE FOURTH EDITION 

In preparing this edition the text has been corrected, 
much of it has been rewritten, and distinctive headlines 
have been added wherever it seemed that greater clearness 
could be attained. The chapters on Purification of Water 
Supplies and on Sewage Disposal have been brought 
down to date, and a chapter on Textiles and one on 
Poisons and their Antidotes have been added. 

Instructors who use this book will find that an occasional 
visit, with the class, to some industrial establishment will 
add greatly to the interest. In almost every community 
there may be found gas, water, or electric light plants, and 
ice plants, bakeries, confectionaries, canning factories, 
creameries, and vinegar factories are common. It is an 
excellent plan also to visit and report on the heating and 
ventilating systems in school buildings, churches, large 
halls, and theaters, and to make tests upon the composition, 
temperature, and humidity of the air which is supplied. 

In the laboratory work the student should be required 
to write out full descriptions of all the work performed, 
with conclusions upon the results obtained. This is the 
only way to make the laboratory work of any permanent 
value. 

The author is indebted to Professor C. C. Young for 
valuable assistance in preparing this edition. 

Lawrence, Kan., 
April 1, 1917. 

vii 



CONTENTS 

PAGE 

Introduction xxv 

PART I 

SANITARY AND APPLIED CHEMISTRY 

CHAPTER I 

The Atmosphere 

History — Proof that air has weight — Experiments of 
Galileo, Torricelli, and Lavoisier — Experiments by 
Cavendish and by Bunsen, Leroy, and Regnault — 
Recent discoveries by Ramsay and Rayleigh — 
Methods used for detecting argon and helium — 
Composition of the air — Experiments to illustrate 
composition of air — Proof that air is a mechanical 
mixture — Methods used for analysis of air — Oxygen 
in expired air — Moisture in the atmosphere — Proof 
that moist air is lighter than ordinary air — Experi- 
ments illustrating the presence of moisture in air — 
Carbon dioxid in free air and in closed rooms — 
Effect of impure air upon the system — Experiments 
to show the amount of carbon dioxid in the air — 
Nitric acid, ammonia, and other impurities in the 
atmosphere — Hydrogen peroxid — Ozone and its 
properties — Experiments upon ozone — The effect 
of carbon monoxid upon the system — Substances in 
suspension in the air — Methods of studying the dust 
of the atmosphere — Bacteria in city air — Micro- 
organisms not abundant at great altitudes — Infec- 
tious diseases readily propagated by dust — Decrease 
ix 



CONTENTS 



in tuberculosis — Vacuum cleaners — Experiments to 
show presence of arsenic in papers and fabrics — 
Injurious trades — Composition of ground air — 
Source of the impurities in ground air — Effects of 
ground air upon the system — Offensive gases . . 1 

CHAPTER II 

Fuels 

History — Combustible elements in fuels — How heat is 
produced by combustion — Cellulose, the basis of 
ordinary fuels — Wood as fuel — Amount of water 
in different woods — Effect of drying upon wood — 
Composition of wood ashes — Charcoal — Method 
of making charcoal — Peat — Occurrence and prepa- 
ration — Coal — Characteristics of different kinds of 
coal — Composition of different coals — The analysis 
of coals — Briquettes — Petroleum coke — Natural 
and artificial gases as fuel — Advantages of gas as 
fuel — Burners used with gas — Composition of 
natural gas — Gasoline — Kerosene — Wood alcohol 
— Grain alcohol 26 



CHAPTER III 

Heating and Ventilation 

Common methods of heating — Use and economy of the 
fireplace — The stove as a heating device — Use of 
the hot-air furnace — Use of steam with direct and 
indirect radiation — Advantages of hot- water heat- 
ing — Electricity as a source of heat — Ventilation 

— Why little attention is paid to this subject — 
Necessity for ventilation — Amount of air used up 
in respiration — Heat retention a cause of discomfort 

— Contamination of air by lights — Properties of im- 
pure air — Amount of fresh air necessary to health — 
Crowd poisoning — Conditions necessary for good 



CONTENTS XI 

PAGE 

ventilation — Mechanical system of ventilation — 
Devices used for ventilating ordinary rooms — Ex- 
periments upon air currents and temperature . . 39 

CHAPTER IV 

Lighting 

Sources of artificial light — Solid, liquid, and gaseous light- 
producing substances — The candle flame — Experi- 
ments with the candle flame — Use of gas for illuminat- 
ing purposes — History of the development of artificial 
light — Candles as a source of fight — Composition of 
candles — Method of making candles — Use of kero- 
sene for lighting — Sources of coal oil and method of 
making — Distillates from Pennsylvania petroleums 

— Adulteration of kerosene — Experiments to show 
the flash point of oils — History of illuminating gas 

— Method of making gas — By-products in gas 
manufacture — Method of making water gas and 
its properties — Preparation and properties of air 
gas — Pintsch gas — Blaugas — Calcium carbid and 
its use in making acetylene — Use of acetylene on 
automobiles — Composition of illuminating gases — 
Experiments upon coal gas — Experiments upon 
acetylene gas — Lamps used for the burning of oils 

— Incandescent gas lights — Method of making 
mantles and their composition — Advantages of in- 
candescent lights — Electric lights — The ideal light 

of the future — Table of light efficiencies ... 54 



CHAPTER V 

Water 

Impurities in water — Source of impurities in water — 
Character of rain, river, lake, and well waters — 
Mineral waters — Experiments upon mineral sub- 
stances in water — Hard waters — Disadvantages of 



Xll CONTENTS 



the use of hard water — Experiments on hard water 
— Organic impurities in water — Source of these 
impurities — The sanitary analysis of a water — 
Meaning of the presence of free ammonia, albuminoid 
ammonia, nitrates, nitrites, and chlorin in a drinking 
water — Experiments to determine the quality of 
water — Analysis of city water supplies — Table — 
Drinking water and disease — Effect of suspended 
matter in water — Organic impurities in water — 
Illustration from the city of Messina — Illustration 
from the Valley of the Tees, England — Illustration 
from Plymouth, Pennsylvania — Illustration from 
Hamburg, Germany — Illustration from Lausen, 
Switzerland — Danger from sewage pollution — The 
cause of pollution of ordinary wells . . ■ .71 



CHAPTER VI 
Purification of Water Supplies 

Natural purification — Processes used — Methods of pu- 
rification — Coagulation and sedimentation — His- 
tory — Artificial purification — Slow sand filtra- 
tion — Construction of filters — Cleaning the filter 

— Rapid sand or mechanical filtration — Method of 
operation — Water softening — Reactions involved 

— Disinfection of water supplies — Use of hypo- 
chlorite of lime — Use of liquid chlorin — Use of 
ultra-violet light — Household purification of water 

— Domestic filters — Boiling the water — Use of 
ozone and of ultra-violet fight for household purifica- 
tion — Effect of freezing — Water supplies of cities 

— Per capita amount supplied — Surface waters 
collected in impounding reservoirs — Water supplied 
by small lakes — Water supplied from the Great 
Lakes — Water supplied from rivers — Cities of 
United States supplied from rivers — Ground water 
supply — Cities supplied in this way — Disadvan- 
tages of ground water — Storage of ground water. 90 



CONTENTS Xlll 

CHAPTER VII 

Sewage : Disposal of Household Waste and Garbage 

PAGE 

Composition of sewage — Oxidation of sewage — Modern 
theories for purification of sewage — Disposal of 
sewage by dilution — The sewage of Milwaukee 
and Chicago — Disposal of sewage by irrigation — 
Intermittent filtration — The septic tank — The Im- 
hof tank — The activated sludge process — Disin- 
fection of sewage — Precipitation of sewage — 
Disposal of household waste — The use of the stove 
or furnace for disposal of waste — Burying in the soil 

— Methods used for disposing of waste in large cities 

— Cremation as used abroad — ''Reduction" of gar- 
bage and utilization as a fertilizer — Municipal refuse 103 

CHAPTER VIII 

Textiles 

Materials used — Origin of materials — Cotton fibers — 
Structure — Mercerized cotton — Flax (linen) — 
Method of treating to obtain fiber — Structure — 
Wool — Description of wool fibers — Wool grease 

— Scouring wool — Silk — How produced — Descrip- 
tion of silk — Artificial silk — Pyroxylin silk — 
Cuprammonium silk — Viscose process — Reactions 
of fibers with alkalies and with acids — Differentia- 
tion between various textiles — Fire-proofing cotton 

— References 114 

CHAPTER IX 

Cleaning: Soap, Bluing, and Bleaching 

Necessity for cleanliness — Cleaning materials act me- 
chanically or chemically — Polishing powder — Borax 

— Ammonia — Cleaning leather, wood, etc. — Sol- 
vents for grease — Cleaning marble — Use of solvents 
upon household fabrics — Removal of grease by 
blotting paper, French chalk, fuller's earth — Treat- 



XIV CONTENTS 



ment of paint spots with oil and turpentine — Sugar 
and acid spots — Ink spots — To clean tarnished 
silver — Cleaning polished brass and copper — Ex- 
periment to remove iron rust 123 

Soap : History of the discovery of soap — Raw material 
used in its manufacture — Process of saponification 

— Method of making soap commercially — Mottled, 
toilet, transparent, and perfumed soaps — Scouring 
soaps and their use — Soft soap — No economy in 
the use of a cheap soap — Advantage of a well-dried 
soap — Theories in regard to the action of soap — 
The use of hard water — Experiments upon making 
soap and in testing its composition — Washing soda 

— Experiments to test a washing powder . . 128 
Bluing : Use of indigo — Prussian blue for making liquid 

blue — Ultramarine and its use as a bluing material 

— Experiments with Prussian blue and with ultra- 
marine — Aniline colors as used in liquid blues . . 136 

Bleaching : Use of bleaching agents — Calcium hypo- 
chlorite — Hydrogen peroxid — Sulfur dioxid . . 138 



CHAPTER X 

Disinfectants, Antiseptics, and Deodorants 

The necessity for using disinfectants and antiseptics — 
The importance of the sense of smell — Tests for 
disinfectants — How bacteria multiply — An ideal 
disinfectant — Use of the following disinfectants and 
antiseptics : Sunlight — Dry air — Dry earth — 
Charcoal — Experiments upon the action of animal 
charcoal — Dry heat and its use — Sulfur dioxid as a 
disinfectant — Carbolic acid and its value — Copper 
sulfate — Iron sulfate — Zinc chlorid — Potassium 
permanganate — Fire, the most effective means of 
destroying disease germs — Steam as used for destruc- 



CONTENTS XV 



tion of germs — Boiling water and how it may be 
used — Chlorid of lime, its value and use — Formalde- 
hyde gas and the method of applying it — Corrosive 
sublimate and its value as an antiseptic . . . 140 



CHAPTER XI 

Poisons and their Antidotes 

Opportunities for becoming accidentally poisoned — 
Chronic and acute poisoning — Poisons and cor- 
rosives — Treatment when poisoned with alkalies — 
With acids — Metallic poisons — Symptoms and 
antidote in case of copper poisoning — Treatment 
for zinc poisoning — Lead poisoning with method of 
treatment — Mercury poisoning — Arsenic, descrip- 
tion and properties — Treatment — Antimony salts 

— Oxalic acid, with method of treatment in case of 
poisoning — Hydrocyanic acid — Phosphorus poison- 
ing — Morphine poisoning — Strychnine — Aconite 

— Carbolic acid — Wood alcohol — Ptomaine poison- 
ing — Carbon monoxid 152 



PART II 
CHEMISTRY OF FOOD 

CHAPTER XII 

Food 

Definition of food — Distinction between food and medi- 
cine — Uses of food — Delicacy of the sense of taste 
— Experience has been our guide in selecting food — 
Variety of food — Value of a mixed diet — Selecting 
food suited to habit and employment — Reasons for 
cooking foods — Food used to build up the tissues 



XVi CONTENTS 



and supply energy — Synthetic foods — Elements 
contained in the body — Amount of substances oc- 
curring in the body — Carbohydrate and nitrogenous 
foods — The cellulose, cane sugar, and glucose groups 
— Proximate substances contained in foods, viz. 
water, fat, carbohydrates, protein, organic acids, and 
mineral salts 161 



CHAPTER XIII 

Cellulose, Starch, Dextrin, Legumes 

Occurrence of cellulose and its properties — Experiments 
upon cellulose — Sources of starch and amount found 
in various cereals — Wheat, its composition — Com- 
parison of different grades of wheat — The composi- 
tion and properties of wheat flour — Analysis of 
different kinds of flour — Milling products of flour 

— Corn — Composition, properties, and uses — Com- 
parison of wheat and corn — Oats — Composition 
and peculiar characteristics — Rye — Its source, com- 
position, and use — Barley — Its composition — Rice 

— Its cultivation, composition, and properties — 
Potatoes — History of the introduction of potatoes 

— Composition and value of potatoes — This tuber 
not suited for use as a staple article of diet — Composi- 
tion of sweet potatoes — Cassava (tapioca) — Its 
source and method of manufacture — The source and 
method of preparing arrowroot — Properties of other 
starches, sago, tous les mois, etc. — Adulteration of 
starch and method used for the detection of adultera- 
tion — Legumes — Cultivation of the members of 
the Pulse Family — Properties of the legumes — 
Composition of peas, beans, and lentils — Experi- 
ments upon legumes — Value of legumes as a food — 
Bananas — Starch — Sources of commercial starch 
and method for making — Experiments upon starch 



CONTENTS XV11 



— Dextrin and method of making — Gums — Inulin 

— Physical properties of starch — Experiments with 
starch grains — Chemical properties of starch — 
Experiments in making starch and to show its proper- 
ties — Experiments upon dextrose — Experiments 
with diastase 170 



CHAPTER XIV 

Bread 

Primitive method of making bread — Two general methods 
of making dough light — First, non-fermentation 
method ; second, fermentation method — Bread not 
raised with fermentation : by the use of eggs, alcoholic 
liquors, ammonium carbonate, baking soda, baking 
soda and molasses, carbon dioxid, baking soda and 
hydrochloric acid, baking soda and sour milk, baking 
soda and cream of tartar — Baking powders — Cream- 
of-tartar powders — Phosphate powders — Alum 
powders — Experiments with baking powders — 
Bread raised by fermentation : first, by use of yeast ; 
second, by use of leaven; third, by the salt-rising 
process — Composition and properties of yeast — 
Method of making yeast — Theory of use of leaven 

— What takes place in the salt-rising process — 
Chemistry of the fermentation of dough — Essentials 
to be noted in making good bread — Construction 
and use of the oven — Temperature used in baking 

— Difference between fresh and stale bread — 
Amount of bread that can be made from a given 
weight of flour — Composition of different kinds of 
bread — Difference between the crumb and crust — 
Starch alone will not sustain life — Value of a mixed 
diet to man — Bread a nutritious food — Value of 
white vs. whole-wheat bread — Patent flour — 



XV1U CONTENTS 



Stale bread and why it is wholesome — Corn bread 

— Why some bread is bad — Adulteration of flour 
and bread — Use of copper sulfate to make bread 
white — Use of alum as an adulterant — Experi- 
ments upon copper sulfate in bread — Experiments 

to detect alum — Occurrence of ergot in flour . . 201 

CHAPTER XV 

Breakfast Foods and Other Special Foods 

Foods for infants and invalids — Breakfast foods and their 
composition — Conclusion in regard to the use of 
breakfast foods — Macaroni, vermicelli, etc., as foods 

— Composition of macaroni . . . . 229 

CHAPTER XVI 

Sugars 

History and classification — Consumption of sugar in 
different countries — Different sugars known to the 
chemist — Classification of sugars — The sucrose and 
glucose groups — Members of the sucrose group — 
Sources of cane sugar — The sugar cane as a source 
of sugar — Cultivating the sugar cane — Extraction 
of the juice — Purification of the juice by the use of 
sulfurous acid — Concentration of the juice in the 
" triple effect" and in the vacuum pan — Use of the 
centrifugal — Treatment of the sirup — Making sugar 
from the sugar beet — History of the development of 
the industry — Use of the diffusion process — Con- 
centration and purification of the juice — Manufac- 
ture of maple sugar — Adulteration of maple sugar 

— Sorghum sugar and its manufacture — Molasses 

— Sugar-refining — Methods adopted in the com- 
mercial centers — Use of the bone-black filter — 
Revivifying bone black — Use of the vacuum pan 
and centrifugal — Granulated sugar — Powdered and 
cube sugar — Experiments to show the properties of 



CONTENTS XIX 

PAGE 

sugar — Composition of raw and of refined sugars 

— Food value of sugars — Maltose, its source and 
properties — Lactose, method of making and 
properties 235 

CHAPTER XVII 

Glucose or Grape-sugar Group 

Processes used for the manufacture of glucose and its 
composition — Uses of glucose — Healthfulness of 
the product — Experiments upon glucose — Invert 
sugars — Levulose — Honey — Composition and 
properties of honey — Experiments with honey . 251 

CHAPTER XVIII 

Leaves, Stalks, Roots, etc., used as Food 

Value of this class of nutrients — Carrots, parsnips — 
Turnips and beets — Leaves as food — Composition 
and value of cabbage — Greens — Asparagus — 
Rhubarb, etc 257 

The use of onions and leeks — Tomatoes and their use — 
Irish moss and its composition — Mushrooms and 
toadstools — The growing of mushrooms and their 
composition — The selection of the non-poisonous 
varieties 260 

CHAPTER XIX 

Composition and Food Value of Fruits 

Some definitions — Composition of fruit at different 
periods of growth — Change in composition as illus- 
trated by analysis of apples — The ripening of fruit 

— Table showing composition of various fruits — 
Value and properties of the different ingredients in 
fruits — Malic acid, citric acid, tartaric acid with 
experiments — Effect of cooking upon fruits . . 263 



XX CONTENTS 



Jams and jellies and their adulteration — Opportunity for 
falsification in this material — Substitutes for jam 
and jelly upon the market — Experiments upon adul- 
terated jellies — Fruit sirups — Flavoring extracts . 270 

CHAPTER XX 

Edible Fats and Oils — Food Value of Nuts 

Composition of edible fats — Digestion of fats and oils — 
Amount of fat in different vegetable and animal sub- 
stances — Use of cottonseed oil in cooking — Use 
of oil of cocoanut — Lard — Method of making the 
different grades, such as refined lard, kettle-rendered 
lard, neutral lard — Adulteration of lard — Manu- 
facture of compound lard, cottolene, cottosuet — Use 
of nuts as food — Composition of the more important 
nuts — Removal of excess of oil from some varieties 
— Value of almonds for food — Use of peanuts as 
food 274 

NITROGENOUS FOODS 

CHAPTER XXI 

Meat 

Concentration of nitrogenous food by animals — Im- 
portance of nitrogen in the animal body — Classifica- 
tion of nitrogenous bodies — Functions of albuminous 
substances — Structure of lean meat — Constituents 
of meat — Composition of beef — Use of animal food 
in different countries — Cooking of meat by roasting, 
broiling, etc. — Beef extracts and their value — Differ- 
ent kinds of meat similar in composition — Fish as a 
cheap and nutritious food — Characteristics of this 
food — Fat and lean fish — Use and food value of 
oysters — Danger from trichina, tapeworms, etc., in 
pork — Experiments upon cooking meat . . . 280 



CONTENTS XXI 

CHAPTER XXII 

Eggs 

PAGE 

Composition of egg white and egg yolk — Use of eggs as 
food — Methods of preservation — Desiccated eggs 

— Proper method for cooking eggs — Experiments 
with egg white and egg yolk 291 

CHAPTER XXIII 
Milk, Cheese, and Butter 

Composition of milk of different animals — Composition 
of various kinds of milk — Experiments upon the 
specific gravity of milk — Composition of butter fat 
and method for its determination — Use of koumiss 

— Experiments to determine amount of butter fat 
and total solids — Cause of the souring of milk — 
Experiments with coagulants — Methods of raising 
cream — Sterilized and pasteurized milk — Condensed 
milk — Its composition — Nature of modified milk 
and how it is prepared — Experiments to detect milk 
adulteration — Cheese — The methods for its manu- 
facture — Description of different kinds of cheese — 
Table showing composition of various cheeses — 
Butter and butter substitutes — Conditions necessary 
for making good butter — Renovated or process butter 

— Manufacture of oleomargarin — Materials used in 
making oleomargarin — Attitude of the government 
toward this industry — Experiments with butter . 295 

CHAPTER XXIV 

NON-ALCOHOLIC BEVERAGES 

General demand for beverages of this class — Amount of 
tea, coffee, and cocoa used in the United States — 
Source of tea — Composition of green and black tea 



XX11 CONTENTS 



— The most important constituents and their prop- 
erties — Experiments upon making a decoction of 
tea and its properties — Paraguay tea — Coffee-leaf 
tea — Coffee — History of its growth — Method of 
cultivation and preparation of the berry — Analysis 
of coffee — Effect of roasting — Adulteration of 
ground coffee — How to make the beverage — 
Coffee substitutes — Cocoa and chocolate — History 
of this product — Method of growing the nuts — 
Composition of chocolate, cocoa, cocoa shells — Value 
of cocoa as a food material — Manufacture of choco- 
late — Experiments upon chocolate — The cola nut 

— Comparison of the effect of the non-intoxicating 
beverages upon the system 312 

CHAPTER XXV 

Alcoholic Beverages 

Use of alcohol from the earliest history of the world — 
Properties of alcohol — Consumption of alcoholic 
liquors in different countries — Classification of 
alcoholic beverages into fermented, malt, distilled 
liquors, and cordials — Per cent of sugar in different 
fruits — Wine — Source of wine — Method of making 

— Fermentation — Aging wine — Chemical reaction 
involved in wine making — Changes produced by 
aging — Composition of various wines — Classifica- 
tion of wines — Why grapes make better wines than 
other fruits — Adulteration and plastering of wines 

— Diseases of wines — Experiments upon wine — 
Cider — Method of making — Adulteration and falsi- 
fication — Beer — Method of making malt — Chemi- 
cal changes involved in manufacture of beer — Com- 
position of some malted liquors — Experiments upon 
beer — Distilled liquors — Definition — Method of 
making alcohol — Distinction between brandy, 
whisky, rum, and gin — Adulteration of fermented 
liquors — Liqueurs — Cordials — Physiological ac- 
tion of alcohol 327 



CONTENTS XX111 

CHAPTER XXVI 

Food Accessories 

PAGE 

Difference between condiments and spices — Common 
adulterants of ground spices — Source and properties 
of cloves, cinnamon, pepper, ginger, nutmeg, mustard 

— Experiments upon spices — Vinegar — Chemical 
changes involved in its manufacture — Material used, 
such as wine, fruit, spirits, malt, etc. — Quick vinegar 
process — Experiments upon vinegar — Salt — Oc- 
currence of salt in different parts of the world — 
Method of obtaining the commercial salt — Composi- 
tion of average samples — Uses of salt . . . 345 

CHAPTER XXVII 

Preservation of Foods — Coloring of Food Products 

Method of preservation of food formerly adopted and those 
in use at present time — Conditions favoring fermen- 
tation and decay — Preservation by canning — Can- 
ning as carried on in large manufactories — Experi- 
ments upon preservation of food — Use of tin cans 

— Experiments upon the composition of the can — 
Recent use of chemical preservatives — Objection 
to the use of these substances — Use and method for 
detection of borax, sodium benzoate, salicylic acid, 
sodium sulfite, and formaldehyde — Coloring of food 
products — Objections to this custom — Use of copper 
to give a green color to pickles — Experiments upon 
food coloring 354 

CHAPTER XXVIII 

Economy in the Selection and Preparation of Food 
— Dietaries 

Proper methods for cooking food — How starch is affected 
by heat — Changes which fats undergo in cooking and 



XXIV CONTENTS 



the effect of heat upon them — Leguminous foods and 
how they should be cooked — A large amount of 
nutriment at small cost — Comparison of vegetable 
and animal foods — Relation between cost of the food 
and its nutritive value — Importance of cooking each 
food in the best way — The use of a steam cooker in 
economizing fuel — The Aladdin oven as an economic 
kitchen utensil — The fireless cooker . . . 365 
Dietaries : History of the study of the composition of food 
— Experiments carried on by the United States gov- 
ernment — Definition of calories — Fuel value of 
different classes of nutrients — Use of the respiration 
calorimeter — A study of the food of different individ- 
uals or classes — Table showing dietaries used in the 
United States and abroad — Standard dietaries as 
estimated by different authorities — The use of smaller 
amounts of proteids than the accepted dietary would 
indicate — The ideal ration — Cost of food and nu- 
tritive ratio — Per cent of income expended for food 
by people of different classes ..... 370 



INTRODUCTION 

A knowledge of the science of chemistry is necessary 
for a proper understanding of so many of the other sciences 
that it is not strange that this subject is so often required 
of students in the lower grades. To know even the rudi- 
ments of physics, botany, biology, geology, mineralogy, 
or physiology, the student must have a fair knowledge of 
chemistry. 

When we consider, however, the arts that have to do 
with modern living, — the eating, drinking, and breath- 
ing, all of which may be prosaic enough in their way, 
— it is evident that the foundation study here also is a 
knowledge of the composition of the substances surround- 
ing us. 

A knowledge of the relations to health of pure air, 
unpolluted water, and wholesome food will have much 
to do with improvement in sanitary conditions, not 
only of students themselves, but, through them, of the 
people at large. The air is usually said to be free, but 
pure air and sunshine cost money, as the crowded tene- 
ments show. The best lighted and ventilated rooms are 
worth the most. Since physicians agree that impure 
air is a predisposing cause of a large per cent of diseases, 
it is of the greatest importance that a knowledge of the 

XXV 



XXVI INTRODUCTION 

danger from this source be diffused among all classes of 
people. 

Water is furnished by the well or cistern at the farm or 
the isolated country house, and for a very large popula- 
tion by a corporation or by the municipality itself. Those 
who use the water from the private source of supply or 
those who furnish it to the multitude of the city, should 
know how water becomes polluted and how to guard 
against disease from this source. 

The food supply is obtained from various sources. 
There is a growing tendency to have food prepared out- 
side the household, and the family learn to depend on 
the baker, the grocer, and the packing house for their 
food. With this tendency comes the temptation to 
those who furnish food ready prepared or dressed, to 
falsify or adulterate it. because they have the opportunity. 

It is certainly time that the people should have some 
practical knowledge of food and medicine. Without this 
knowledge they will continually be imposed upon by 
those who have something to sell which may be worth- 
less as a food, or dangerous as a medicine. 

Just as society claims the right to protect itself against 
epidemics, against polluted water, and against smoke nui- 
sances,, so it is learning that it also has the right to protect 
itself against bad food. The United States and the various 
state and city governments have aided the people gener- 
ously for the past twenty-five years, and by their published 
analyses,, bulletins, and other literature have assisted no- 
tably in molding public sentiment in favor of wholesome 
and unadulterated food. The foundation of the present 
movement seems to be publicity. 

Schools and colleges are beginning to see their oppor- 
tunity to impart a kind of knowledge that is practical 



INTRODUCTION XXV11 

and sane, and so we have the manual training school 
and the agricultural college, as well as instruction in 
domestic science in schools of a lower grade. 

A thorough understanding of the facts of applied 
chemistry will not make the skilled workman, nor will 
the theories of chemistry make the accomplished cook, 
but a broad and thorough knowledge of the underlying 
principles will go very far toward developing common 
sense in hygiene and in the selection and preparation of 
food. 



PART I 
SANITARY. AND APPLIED CHEMISTRY 

CHAPTER I 

THE ATMOSPHERE 

HISTORY 

The early philosophers in the time of Aristotle, 350 B.C., 
thought there were four elements, — earth, air, fire, and 
water, — and that each of these had special properties, 
and they also believed that the air had weight. For six- 
teen hundred years comparatively nothing was done 
except to theorize in regard to the properties of air. 
Then Galileo, an Italian, showed that a copper globe 
filled with air under ordinary pressure weighed less than 
the same globe filled with compressed air. Galileo was 
fortunate in making the acquaintance of Torricelli, also 
an Italian, and at the death of the former, Torricelli 
carried on the experiments. He explained why it was 
impossible to raise water more than thirty-three feet in a 
tube by suction ; that is, that there was not sufficient 
pressure of the air to force the water higher, and he 
also reasoned that a heavier liquid, like mercury, could 
not be raised as far as water. He tried this experi- 
ment and found that mercury could be raised only about 
thirty inches, and noticed that the relation between the 



2 SANITARY AND APPLIED CHEMISTRY 

specific gravity of mercury and that of water was inversely 
proportional to the height to which the two liquids could 
be raised. That is, water can be raised 13.6 times as far 
as mercury. 

The theory that air had weight, and kept the mercury 
or the water up in the barometer tube, was not fully 
adopted when Torricelli died. Pascal, a Frenchman, 
born in 1623, who followed these investigators, said that 
if their theory was true, a column of mercury would fall 
when a barometer was carried to an elevation, so he se- 
cured the services of a friend to carry a barometer to the 
top of a mountain, and the latter was delighted to find 
that as he ascended the mountain the mercury fell. It 
was left to Boyle, an Irishman, born in 1627, to use this 
apparatus, which he called a " barometer" (Gr. baros y 
metron), to measure the weight of the air. 

All this time air was regarded as a simple element, and 
the next epoch in its study was the discovery, by Priestley 
and Scheele in 1774, that it contained the element oxygen. 
It was left for the French chemist, Lavoisier, to correlate 
the discoveries of several chemists, and to show that 
when oxygen was taken out of the air, the gas that re- 
mained was the so-called nitrogen, discovered in 1772 by 
Rutherford. Lavoisier noticed that by heating mercury 
in a confined volume of air the air was contracted one 
fifth in volume, and the mercury was covered with a 
red powder. The air that was left in the vessel would 
not support combustion. When the red powder, which 
is oxide of mercury, was afterwards heated, it gave 
off a gas whose volume was one fifth of the original 
air, and this gas would support combustion with great 
vigor. 

Cavendish made a large number of experiments on the 



THE ATMOSPHERE 3 

air, but it was Bunsen, Le Roy, and Regnault who proved 
that air is not always of the same composition, though 
very nearly so, and that consequently it cannot be a 
chemical compound, but must be a mixture of different 
gases. 

The third era is the recent discovery of argon (in 1894 
and the years following), by two Englishmen, Lord Ray- 
leigh and Professor Ramsay ; and later helium and other 
gases were discovered in the atmosphere. The circum- 
stances that led to the discovery of argon are interesting. 
Lord Rayleigh noticed that the weight of a liter of 
nitrogen obtained from chemicals, as by heating ammo- 
nium nitrite (NH 4 N0 2 = N 2 + 2H 2 0) is 1.2505 grams, 
but a liter of the so-called nitrogen obtained from the air 
weighs 1.2572 grams. It was impossible to account for 
this by assuming errors in the weighings, which were made 
with exceptional care. These men experimented with 
air by passing a strong electric spark through a confined 
volume of air, contained in a tube over mercury, thus 
causing some oxygen and nitrogen to unite, and forming 
an oxid of nitrogen. The latter was absorbed by a 
solution of potassium hydroxid, then more oxygen was 
introduced, and the sparking by electricity was continued, 
until finally only a small residue remained, which could 
not be made to combine with oxygen/ The excess of 
oxygen was then absorbed, and the residual gas was placed 
in a Plticker tube under diminished pressure, and, while 
a current of electricity was passed through it, was exam- 
ined by means of the spectroscope. The spectrum was 
different from that of any known gas. Other substances 
were brought in contact with this gas, but it did not unite 
with them, and the name " argon/' which signifies " in- 
active/' was given to the gas. This gas was also prepared 



4 SANITARY AND APPLIED CHEMISTRY 

from air, after the oxygen had been removed, by passing 
it over red-hot magnesium, which took out the nitrogen 
and left the argon. 

A little later, the element " helium " was found first in a 
mineral Clevite, and afterwards in the air. This element 
had previously been discovered in the atmosphere of the 
sun by the examination of sunlight with a spectroscope, and 
chemists were delighted to find that the gas which they 
obtained from certain minerals, and also from mineral 
springs, was the same as had previously been discovered 
in the sun. More recently the other gases, neon, krypton, 
xenon, were discovered. Since liquid air can now be made 
at a comparatively small expense in large quantities, these 
latter gases may be separated from it by " fractional 
distillation/ J and may thus be more thoroughly studied. 



CONSTITUENTS OF THE AIR 

The average composition of moist air by volume is as 
follows : — 

Pabts per 1000 

Oxygen 207.7 

Nitrogen 773.5 

Water 8.4 

Argon . % 9.4 

Carbon dioxid . . . 3 to .4 

Nitric acid Trace 

Ammonia Trace 

Hydrogen sulfid Trace 

Sulfurous anhydrid Trace 

Helium 001 

Krypton 001 

Xenon 0005 

Hydrogen .03 

Neon 01 



THE ATMOSPHERE 5 

* Experiment 1. To show the weight of air. Fill a glass 
tube about 900 mm. long, closed at one end, with clean, dry 
mercury and invert it over a vessel of mercury. Read the 
height of the column by means of a meter measure. 

* This Experiment and any others marked * if more convenient, may 
be performed by the instructor in the presence of the class. 

* Experiment 2. Read a good barometer, and compare 
reading with that obtained in the tube. 

* Experiment 3. To show the effect of moisture in air, or 
the vapor tension of water, add a small drop of water to the 
mercury, in Experiment 1 by putting it beneath the surface of 
the mercury in the tube, with a glass tube bent upward at the 
lower end. Record the difference of level. 

Experiment 4. To prove the composition of air, melt some 
phosphorus 1 in one end of a 100 cc. eudiometer tube or plain glass 
tube, sealed at one end and tightly closed with a soft cork. The 
phosphorus may be melted by immersing the end of the tube 
containing the phosphorus in boiling water for a few minutes. 
Throw the phosphorus along the tube by a quick swing, and it 
should take fire. Immerse the corked end of the tube in a 
cylinder of water, remove the cork while still under water, and 
the water will rush in. When the contents of the tube has 
become of the same temperature as the air, read the level of 
the water inside the tube, first making it of the same height 
inside as outside, by lowering or raising the tube. Calculate 
the per cent of oxygen in the air. 

AIR A MIXTURE 

As previously stated, these gases, oxygen, nitrogen, etc., 
are mechanically mixed in the air. This may be proven as 
follows : — 

1st, Because the air in different localities has different 
composition. 

1 In all experiments with phosphorus, observe the precaution 
never to touch it with the hands, as it ignites readily and produces 
severe burns. 



5 SANITARY AND APPLIED CHEMISTRY 

2d, Because air dissolved in water is richer in oxygen 

than ordinary air. 
3d, Because the mixture of oxygen and nitrogen in the 

proportion of air cannot be made to combine by 

a spark to form air. 
4th, If liquid air is allowed to evaporate, the nitrogen 

goes off first, leaving nearly pure oxygen. 

VITIATED AIR 

Air is vitiated or rendered too impure for respiration 
from a variety of causes. Among these may be mentioned 
an increase in the amount of carbon dioxid, and a conse- 
quent decrease in the amount of oxygen ; a lack of suffi- 
cient moisture, and an excess of moisture ; by the presence 
of suspended impurities of a vegetable, animal, or mineral 
origin ; by poisonous gases, from illuminating gas, sewers, 
or manufactories ; by the presence of the impurities that 
are due to respiration, and by a mixture with ground air. 

COMPOSITION OF AIR 

The methods used for the analysis of air are usually 
volumetric. From a sanitary standpoint, the most 
practical thing is to determine the amount of some of 
the substances which are present in small quantity, but 
which are really of great hygienic importance. 

It is assumed that we are familiar with the properties of 
oxygen, a gas that assists in combustion, causes a spark to 
burst into flame, and is absolutely necessary to respiration. 
The amount of oxygen found in the air in different locali- 
ties varies, according to Bunsen, within narrow limits from 
20.97 % to 20.84 %. These results were confirmed by 
Regnault, R. Angus Smith, Leeds, and others, who made 



THE ATMOSPHERE 7 

analyses of air from different parts of the world. In the 
crowded tenement districts the air has been found to 
contain as low as 20.60 % of oxygen. 

The air as it leaves the lungs contains about 79 % of 
nitrogen and argon, and only 16 % of oxygen, for this air, 
instead of containing the normal amount of carbon dioxid, 
now contains about 4.4 %. The oxygen has been con- 
sumed in the vital processes. The human system is very 
susceptible to the disturbance of the normal proportions 
of the gases in the atmosphere, and this is one of the 
causes for discomfort in a crowded room. 

Nitrogen, on the other hand, has properties that are, to 
some extent, opposed to those of oxygen. Nitrogen does 
not burn, does not support combustion, is not poisonous, 
and is, in fact, an inert gas. In combination, however, 
it is of special importance, as in nitrates, explosives, 
coloring matters, and alkaloids, as well as in some vege- 
table substances, and in nearly all animal tissues. 

HUMIDITY OF AIR 

Water in the air is necessary both for the growth of 
vegetable and animal life. The amount of vapor that 
air contains depends, of course, upon the temperature. 
The higher the temperature, the greater the amount of 
moisture the air will hold without precipitation. When 
air contains as much moisture as, at a given temperature, 
it is capable of holding, it is said to be saturated. Humid- 
ity has reference not to the actual amount of vapor present, 
but to the proportion which this bears to the possible 
maximum at that temperature. At 0° C, a cubic meter 
of air will hold only 4.87 g. of water ; at 10° C, 9.92 g. ; 
at 15° C, 12.76 g. ; at 20° C, 17.16 g. ; and at 32° C, 
33.92 g. 



8 SANITARY AND APPLIED CHEMISTRY 

If the air is absolutely dry, plants wither and die, and 
animals do not thrive, since they lose water too rapidly by 
evaporation. The amount of moisture in the air varies 
from ^-th to g^th of the volume, and from 65 % to 
75 % of saturation is regarded as most beneficial to 
health. If the humidity of the air is 90 % of saturation, 
and the temperature is 90° F., the conditions are almost 
unbearable, while at the same temperature, with 50 % of 
humidity, it is not uncomfortable. Air that is saturated 
with moisture does not permit the heat of the earth to 
radiate so rapidly. At night, as the air cools, we get a 
deposit of dew. It is well to remember that the " dew- 
point " or the temperature at which a deposit of moisture 
begins varies with the amount of moisture in the air. The 
earth cools more rapidly on clear nights, hence in cold, clear 
weather there is greater danger of frost. The amount of 
moisture thrown off from the lungs and skin is about one 
third of that taken in with the food. This would mean 
that from 1 J to 2 lb. of water would be given off per 
capita every 24 hours. Moist climates are adapted to the 
treatment of certain diseases, while we are familiar with 
the action of dry air, such as that of Colorado, Arizona, 
and California, in the treatment of tuberculosis. 

As air is essentially a mixture of one part of oxygen with 
four parts of nitrogen and a varying amount of water 
vapor, the weight of a liter of air would be equal to the 
sum of these constituents, and the way in which this 
weight will vary can be seen from the following figures : — 

The weight of a liter of nitrogen is ... 1.25 grams 
The weight of a liter of oxygen is .... 1.43 " 
The weight of a liter of water vapor is . . .81 " 

From the composition of the air above noted, a liter of 
dry air would contain practically 



THE ATMOSPHERE 9 

800 cc. of nitrogen weighing 1.000 g., and 

200 cc. of oxygen weighing 286 g. 

Giving a total weight of air as . . . . 1.286 g. 

Since water vapor is lighter than either nitrogen or 
oxygen, and since it displaces its own volume of these 
other gases, air containing water vapor will be lighter 
than an equal volume of dry air. 

To illustrate : Suppose we have a sample of air con- 
taining 5 % of water vapor, then a liter of this air would 
contain 

760 cc. of nitrogen weighing 950 g., and 

190 cc. of oxygen weighing 272 g., and 

50 cc. of water vapor weighing 0405 g. 

Total 1.2625 g. 

Experiment 5. To show the presence of moisture in the 
air, fill a wide-mouthed flask of about 1 liter capacity with 
pounded ice or snow. Clean it thoroughly on the outside and 
wipe it dry. Suspend it in the room and notice after a short 
time the abundant deposit of moisture from the air. 

Experiment 6. Suspend two thermometers that read alike 
side by side on the iron stand in the laboratory. Make a note 
of the readings. Fasten about the bulb of one of them by means 
of a rubber band a wad of cotton that has been thoroughly 
soaked in water, and place in a draught of air, or fan moder- 
ately. Note after a short time, when the mercury has become 
stationary, the difference in temperature of the two thermom- 
eters. Will there be this difference if the air is absolutely 
saturated with moisture ? 



10 SANITARY AND APPLIED CHEMISTRY 

CARBON DIOXID IN AIR 
Carbon dioxid (CO2) finds its way into the air : — 

1. By combustion. 2. By respiration. 

3. By the decay of vegetable matter. 

4. By chemical action. 5. By volcanic action. 
6. By the escape of ground air. 

This gas is not poisonous, as this term is ordinarily 
used, but animals may be said to drown in carbon dioxid 
gas. The amount of this gas in 1000 parts of air varies 
in different places : for instance, in Munich it was found 
to be .051; in Scotland, .053; on London streets, .038; 
at Lake Geneva, .044. This is for the outdoor air. More 
recent investigations show that normal outdoor air con- 
tains between .03 and .04 parts of carbon dioxid. The 
air in crowded rooms is frequently extremely impure, as 
shown by the following analyses : * — 

CARBON DIOXID IN CLOSED ROOMS 

Parts per 1000 

A schoolroom in England contained . . 2.41 

Sitting room in a private house . . . 3.04 

Public library 2.06 

Courthouse gallery 2.90 

Printing office 1.49 

Tailor's workshop 3.06 

Boot and shoe finisher's shop . . . . 5.28 

Surrey Theater 2.18 

Standard Theater 3.20 

Girls' schoolroom 7.23 

Schoolroom in New York City . . . . 2.80 

Bedroom with closed windows . . . 2.30 

Average of 339 experiments in mines . 7.85 

Sleeping cabin of a canal boat .... 9.50 

1 Fox, "Sanitary Examination of Water, Air, and Food," p. 204. 



THE ATMOSPHERE 11 

It is no doubt true that the amount of carbon dioxid in 
the air has something to do with the disagreeable sensa- 
tions experienced in a crowded room. 

Some of these are : — 
Headache 
Stupor 

Restlessness 

Craving for excitement 
Fainting 
Nausea 

Lowered Vitality. 

According to the experiments by Drs. Billings, Mitchell, 
and Bergay, it is shown that the disagreeable effects pro- 
duced upon the system by impure air are due to the fol- 
lowing causes : the reduction in the amount of oxygen, 
the increase of carbon dioxid, excess of moisture, the high 
temperature, the dust and disagreeable odors, — in fact, to 
all these combined. 

Some recent experiments on the effects of atmosphere 
deficient in oxygen on animals and on man l indicate 
that an atmosphere deficient in oxygen begins to affect 
man when the percentage of oxygen is about as low as 
that affecting canaries and mice. When the amount of 
oxygen is reduced to about 7 %, these animals show 
considerable distress and man is in danger of dying. 

We know that considerable pure carbon dioxid is not 
especially injurious, as workmen in breweries and other 
manufactories are not affected by even a larger amount 
of carbon dioxid than is found in the air of a crowded 
room. 

1 Technical Paper 122, Dept. of Interior, Bureau of Mines. 



12 SANITAKY AND APPLIED CHEMISTRY 

According to the experiment of Cowles and Feilmann, l 
air that contains 14 % of carbon dioxid, and has remain- 
ing only 18.1 % of oxygen, will extinguish a candle flame. 
In the absence of carbon dioxid, air to which 22 % of 
nitrogen has been added will extinguish a candle flame. 
Expired air has about the same composition as that pro- 
duced by the burning of a candle in an inclosed space 
until the candle goes out. As an atmosphere, even as 
impure as this, could be breathed without causing in- 
sensibility, the common test for the air of a well, by letting 
down a burning candle, is within the limit of safety. 

For the determination of carbon dioxid, many forms of 
apparatus have been invented. Usually a measured 
amount of air is passed through a solution of barium 
hydroxid or calcium hydroxid, and the barium or calcium 
carbonate thus formed is filtered off and weighed. The 
reaction, where barium hydroxid is used, is as follows : — 

Ba(OH) 2 + C0 2 = BaC0 3 + H 2 0. 

Experiment 7. To show the production of carbon dioxid 
by combustion, attach a funnel, by means of a tube bent twice 
at right angles, like an inverted " f|, w to a Woulfe flask con- 
taining limewater. The end of the tube should be a little below 
the surface of the limewater. Through the other opening in 
the flask put a cork and glass tube, bent at a right angle, and 
aspirate air through the limewater. Note that the small amount 
of carbon dioxid in the air does not make the limewater turbid. 
Place a lighted candle beneath the funnel, and notice the forma- 
tion of carbon dioxid. Write the equation for the combustion 
of the carbon of the candle, and for the precipitation in limewater. 

Experiment 8. Repeat the above experiment with a small 
jet of illuminating gas under the funnel, and notice whether 
the limewater becomes as quickly turbid as with the candle. 

1 Jour. Soc. Chem. Ind., Vol. 13, p. 1155; Vol. 14, p. 345. 



THE ATMOSPHERE 13 

Experiment 9. To show the presence of carbon dioxid in 
the breath, arrange an apparatus by the use of two Erlen- 
meyer flasks, or wide-mouthed bottles fitted with corks, each 
provided with two holes fitted with glass tubes, so arranged 
that air may be drawn in through limewater in one flask at each 
inspiration, and may be passed out through limewater in the 
other flask at each expiration. The tubes used for the inspira- 
tion and for the expiration of the air may be held side by side 
in the mouth by the use of rubber bands, although a better 
method is to use a Y tube to connect them. Notice that the 
limewater is turbid in one flask and not in the other. Why? 

Experiment 10. To determine the amount of carbon di- 
oxid gas in the air, use the new Wolpert apparatus, which 
depends on the amount of air that will be necessary to decolorize 
a slightly alkaline solution of phenolphthalein. 



QUANTITATIVE DETERMINATIONS 

* Experiment 11. Another method for the determination 
of the amount of carbon dioxid in the air is the following, known 
as Pettenkofer's method. Determine the strength of a solu- 
tion of limewater or baryta water against a standard solution of 
oxalic acid, containing 2.84 grams of oxalic acid per liter, by 
placing 25 cc. of limewater in a porcelain dish, and running 
into this, through a graduated burette, enough oxalic acid to 
exactly neutralize it, using a strip of yellow turmeric paper as an 
outside indicator. This equation shows what takes place : — 

H2O2C2O2 + Ca(OH) 2 = Ca0 2 C 2 2 + 2 H 2 0. 

Find the exact capacity of a glass-stoppered bottle of 4-6 liters 
capacity, and put a sample of the air to be tested in this bottle 
by means of a bicycle pump or a bellows. Measure into this 
bottle 50 cc. of limewater, shake, and set aside for 6 or 8 hours. 
Take out with a pipette 25 cc. of the limewater without shaking, 
so as to get as little calcium carbonate as possible, and titrate 
this with the standard oxalic acid ; and the difference between 

* See note on p. 5. 



14 SANITARY AND APPLIED CHEMISTRY 

the amount used and the amount required to neutralize 25 cc. 
of the untreated limewater represents the effect due to the car- 
bon dioxid gas in the air. The action of the carbon dioxid on 
the limewater is represented by the equation : — 

C0 2 + Ca (OH) 2 = CaC0 3 + H 2 0. 

The oxalic acid used is of such strength that 1 cc. corresponds 
to 0.5 cc. of carbon dioxid gas. Subtract 50 cc. from the ca- 
pacity of the bottle for the space occupied by the limewater. 
Calculate the parts of carbon dioxid per 10,000 parts of air. 
This may be reduced to standard conditions of temperature 
and pressure by the usual methods. (See " Public Health 
Laboratory Work," Kenwood, p. 194.) 

An example of the calculation is as follows : Suppose it 
required 30 cc. of oxalic acid solution to neutralize 25 cc. of 
limewater, and the 25 cc. of limewater from the bottle of air 
is neutralized by, say, 27 cc. of the oxalic acid solution. This 
means that the carbon dioxid in the air was equivalent to 3 cc. 
of oxalic acid solution. 1 cc. of this solution = 0.5 of carbon 
dioxid, then 3 cc. = 1.5 cc, which multiplied by 2 for the other 
25 cc. of lime water in the bottle gives 3 cc. of carbon dioxid. 
If the capacity of the bottle was 4000 cc, subtract 50 cc. from 
this = 3950 = volume of the air taken. Hence we calculate 
.0759% of carbon dioxid in the air, or 7.59 parts in 10,000 parts 
of air. 

The American Public Health Association's Committee 
on Standard Methods for the Examination of Air x rec- 
ommend the use of a modified form of the Petterson- 
Palmquist apparatus, which depends on the principle of 
treating a measured quantity of air with potassium 
hydroxid, and again measuring it, thus giving the car- 
bon dioxid by difference. Haldane's apparatus is quite 
similar and gives excellent results, in the hands of an 
experienced operator, in about five minutes. 

1 Am. Jour. Pub. Health, Vol. Ill, p. 81 ; Vol. VII, p. 66. 



THE ATMOSPHERE 15 

CARBON MONOXID IN AIR 

Carbon monoxid (CO) is sometimes found in the air 
of inhabited rooms, on account of insufficient ventilation 
or leaky joints in furnaces. Red-hot cast iron will also 
transmit the gas. As it is extremely poisonous, — less 
than one half of one per cent in air being fatal to human 
life, — it is of the utmost importance that it be excluded 
from the air of our dwellings. Fortunately, although 
carbon monoxid itself has no odor, it is usually mixed 
with some other gas that has a decided odor. In coal gas 
it is mixed with the sulfur compounds which are so 
readily detected by smell, and in escaping furnace gases 
it is usually accompanied by sulfur dioxid, which has the 
familiar odor of a burning match. When formed by 
burning charcoal, there is scarcely a perceptible odor. 
(See Ventilation, p. 45.) 

OTHER GASES IN AIR 

Nitric acid in the air is largely a result of the oxidation 
of the ammonia. Some nitrogen oxids are formed from 
free nitrogen by the lightning flashes in the air. The 
nitric acid, when washed into the soil by the rains, is of 
great value as a fertilizer for growing plants. 

Ammonia is formed partly by the decay of vegetable 
and animal matter in the soil and partly by other chemical 
processes. Ammonia would naturally unite with carbon 
dioxid, making ammonium carbonate, or with the nitric 
acid, making ammonium nitrate ; and both the acid and 
the base in this latter salt are useful when washed down 
by the rain, in enriching the soil. The amount of ammonia 
varies from 0.1 to 100 volumes in a million volumes of air. 



16 SANITARY AND APPLIED CHEMISTRY 

Hydrogen sulfid (H 2 S) will not ordinarily be found in pure 
air, but in cities, where there is decomposition of organic 
matter and sewer gas, it may be frequently detected by its 
disagreeable odor. Sulfurous anhydrid is not a constit- 
uent of the pure air of the country, but where soft coal is 
burned, or where there are manufactories operating, this 
gas will be found. Sulfur dioxid is quite noticeable in 
the vicinity of chemical works, especially where zinc, 
lead, and copper ores are smelted. An extremely small 
quantity of the gas in the air is fatal to vegetable life, 
so that trees and shrubs in the vicinity of smelters and 
chemical works, especially on the side toward which the 
prevalent wind carries the fumes, are killed. 

Hydrogen peroxid (H 2 2 ) is a powerful oxidizing agent 
which is present in small quantities in the air and in rain 
and snow water. It is probable that some of the effects 
often ascribed to ozone are really due to hydrogen 
peroxid, as it has similar oxidizing action. A 3 % solu- 
tion of hydrogen peroxid in water is the well-known com- 
mercial disinfectant. 

OZONE 

There is an interesting form of oxygen known as ozone. 
It was noticed many years ago that a peculiar smell ac- 
companied a thunderstorm, and this as well as the light- 
ning was ascribed to evil spirits. As early as 1785 Van 
Marum noticed a peculiar odor in the vicinity of an 
electrical machine, and recognized that it was the same 
as that accompanying lightning discharges. It was not 
till 1840, however, that Schonbein, a Swiss chemist, dis- 
covered ozone, and showed that electricity changes oxygen 
to ozone. 

In addition to the production of ozone by electrical dis- 



THE ATMOSPHERE 17 

charges, it is formed in many other ways, as by the slow 
oxidation of phosphorus, by the partial combustion of 
ether, and by the action of sulfuric acid on potassium 
permanganate or on barium dioxid. Ozone slowly changes 
back to oxygen at 100° C. and rapidly at 300° C. It has 
been shown that ozone can be smelled if present in the 
proportion of one volume of ozone to 2| million 
volumes of air. When a known volume of ozone is 
changed back to oxygen, there is an increase in volume. 
This is due to the fact that a molecule of ozone contains 
three atoms and a molecule of oxygen, two atoms, hence : — 



<°V°h 



3(0 = O). 



Ozone is a very powerful oxidizing agent and unless 
greatly diluted has an irritating action on the mucous 
membrane. Since many coloring substances are destroyed 
by ozone, it is often used as a bleaching agent. It is 
also used for the sterilization of water and the purification 
of air on a commercial scale. Air is thus purified from 
traces of organic matter by oxidation. There is con- 
siderable controversy and authorities differ as to whether 
the bacteria in the air are destroyed by ozone. The air 
of the underground railway in London is purified by 
blowing in ozone with the fresh air, and the air of hos- 
pitals is often purified in the same way. 

It was for a long time supposed that the test with " ozone 
paper " was a positive proof that ozone existed in the air, 
but as other substances, such as some of the oxids of nitro- 
gen, color ozone paper in a similar way, there is still some 
doubt as to whether it exists in appreciable quantities in 
the atmosphere. 



18 SANITARY AND APPLIED CHEMISTRY 

Experiment 12. To make " ozone paper," mix about 5 g. 
of starch with 20 cc. of cold distilled water. Pour this into 
a beaker containing 100 cc. of boiling water, in which has been 
dissolved about a gram of potassium iodid. Heat the mixture 
for a moment. Soak strips of white filter paper in this solution 
and allow them to dry in pure air. The paper turns blue in the 
presence of ozone. 

Experiment 13. To make ozone, turn a static electrical ma- 
chine and test the air in the vicinity by means of moist ozone 
paper. 

Experiment 14. Heat a large glass rod in a Bunsen burner. 
Pour a few drops of ether into a medium-sized beaker and move 
the rod around in the vapor of ether. Test this vapor for ozone, 
which with other products is probably present. 

Experiment 15. Cut some phosphorus in thin slices under 
water, and place them in a cylinder with a little warm, not hot, 
water in the bottom, but not enough to cover the phosphorus. 
Suspend some pieces of moist ozone paper in the jar and place 
a cover over it. After a time the paper will turn blue, showing 
the presence of ozone. 



SUBSTANCES IN SUSPENSION IN THE AIR 

Although the air is apparently clear and transparent, 
yet we have only to admit a ray of sunlight into a room to 
see the dust which is in the air. " Minute particles of any- 
thing and everything that exists upon the earth are liable 
to be mingled in the air that rests on it. These suspended 
matters are furnished by the animal, vegetable, and mineral 
kingdoms. " 1 We get, in the animal kingdom, the debris 
of little insects suspended in the atmosphere — eggs and 
other substances. From the vegetable kingdom we get 
spores of fungi, bacteria, pollen of plants, seeds of all kinds, 

1 Fox, "Water, Air, and Food," p. 264. 



THE ATMOSPHERE 19 

t 

particles of straw, etc. From the soil, the dust of inorganic 
composition, such as sand, iron oxid, lime, mud from vol- 
canoes, particles of carbon, sulfur, and, in the vicinity of the 
ocean, sodium chlorid and other minerals carried long dis- 
tances by the wind. 

EXAMINATION OF AIR 

The air of sick rooms, hospitals, and prisons has been 
carefully examined, and a microscopic study has been made 
of the dust collected. It has been found to contain a 
variety of organic matter. The first method of examina- 
tion is by passing a known quantity of air through a tube 
closely packed with sterilized cotton, and then washing 
the cotton and examining the wash water. By this 
means we can arrive at the number of spores per liter of 
air. A known volume of air may be drawn through sand 
or sugar and sterilized liquid gelatin added to this, and 
finally the number of colonies in the gelatin may be 
counted. A more convenient method, however, is what 
is known as the plating method, in which we pour into a 
series of shallow glass vessels, called Petri dishes, a nutrient 
medium which becomes solid on cooling. To this the dust 
particles readily adhere. This gives a moist, sticky surface, 
which can be easily protected by tightly fitting covers. 
When we desire to examine the air in any locality, one 
of these vessels is opened and exposed to the air for a 
specified time, say 25 min. In this way it is possible to 
compare the air in different localities. By counting 
colonies, each one of which presumably consists of the 
offspring of a single germ, the following numbers of 
bacteria were found under different conditions in New 
York City : — 



20 SANITARY AND APPLIED CHEMISTRY 

Central Park, dust blowing 49 

Union Square 214 

In a private house 34 

Dry goods store 199 

Broadway and 35th St. 941 

When the street was being cleaned 5810 

In a house called clean 180 

In a filthy house 900 

In a dirty schoolroom with natural ventilation . . 2000 

Average in hospitals and dispensatories .... 127 

There are, in fact, more living microorganisms in the air 
than the above results would indicate, for many germs do 
not find in the nutrient medium conditions favorable to 
development. It is understood that these organisms are 
of widely different character, although they are generally 
either molds, yeasts, or bacteria. It is estimated that 
in the open country in a cubic inch of air there may be 
2000 dust particles, 3,000,000 in the air of city streets, 
and 30,000,000 in that of inhabited rooms. 1 While micro- 
organisms are very abundant in the air of towns, there 
are hardly any at great heights and at sea. Pasteur 
exposed a large number of flasks of broth at an altitude 
of 6000 feet, and obtained a growth in but one. Tyndall 
exposed twenty-seven flasks at 8000 feet and got no growth 
whatever. Dr. Fisher has shown that on the ocean 120 
miles from land the air is usually free from organisms and 
that at a lesser distance — 90 miles, for example — it 
contains but few. 2 

Some recent experiments (1914) on city air have been 
made by M. C. Whipple. 3 He secured the samples of 
air for bacterial and dust examination by drawing air 
by means of a small fan motor through an adaptor tube 

i Nature, Vol. 31, p. 265; Vol. 41, p. 394. 

2 Harrington, "Practical Hygiene," p. 233. 

3 Am. Jour. Pub. Health, Vol. V, p. 725. 



THE ATMOSPHERE 21 

containing a layer of sand. Later this was washed out of 
the tube by the use of sterile water, and for the collection 
of the dust particles a half inch layer of resorcinol crystals 
was employed. These crystals are then dissolved in 
clear water, and the particles remaining are examined 
and counted under the microscope with a 16 mm. objec- 
tive. It was found that there were 18,000 particles per 
cubic foot in air over Long Island Sound, 27,000 at the 
57th story of the Woolworth Building in New York City, 
at a time when the street air showed 221,000 particles. 
In all cases the air of schoolrooms contained more par- 
ticles of dust and more bacteria than the outside air. 
In the elevated railway cars in Boston, the number of 
dust particles was often very high, being in one instance 
3,415,000 per cubic foot. 

EFFECTS OF DUST 

Dust, however, is of great importance on account of its 
influence upon the precipitation of rain, upon clouds and 
fog. 

There are certain diseases, such as consumption, 
diphtheria, smallpox, yellow fever, Asiatic cholera, 
scarlatina, measles, etc., which are called infectious, and 
which are often propagated by bacteria in the air. Much 
attention has been paid to the propagation of consump- 
tion, and the Bacillus tuberculosis has been quite 
thoroughly studied. It is stated that in Europe about 
a million persons die annually from consumption, and 
one tenth of all the people of the civilized world fall 
victims to this disease. Dr. Francine (J. Am. Med. 
Assn., 1905) says that 110,000 persons die every year in 
America from consumption. This is a disease in which 
the germs from the dry sputa are carried in the air, lodged 



22 SANITABT AM) APPLIED CHEMISTRY 

in the air passages, and, if they find the system in the right 
condition, they commence to grow and carry on their 
deadly work. 

On account of a better understanding of the disease, 
and more rational methods of treatment, and especially 
because of the great effort that has been made to dis- 
seminate information in regard to the cause and cure of 
tuberculosis, and the better housing and sleeping habits 
of the people, and the wide-extended use of the sleep- 
ing-porch, the mortality from tuberculosis has been much 
decreased within the last - r years. Eecent figures show 
that the death rate from tuberculosis of the lungs in the 
registration area of the United States has diminished from 
175 per 100,000 population in 1900 to 125 in 1914. In 
American cities the death rate from tuberculosis has 
diminished since 1870 Cram 340 per 100,000 to 150 in 
1914, 

VACUTM CLEAXER5 

Too much can hardly be said in favor of the modern 
method of removing dust and dirt by the use of vacuum 
cleaners. The use of these machines, which need not be 
elaborate or expensive is : ::e of the most important steps 
that has been made for years in the direction of keeping 
the air of our dwellings free from dust. Instead of stir- 
ring up the dust by means of a broom and duster, to have 
if settle again upon the floor and furniture, the vacuum 
cleaner removes it from the room. 

a^si:*:: r>" ts-ail paper 

A Few years ago there was a great outcry against arsenic 
in wall paper, and it was said that the dust of many rooms* 
in which the walls were hung with ordinary paper, was 



THE ATMOSPHERE 23 

laden with arsenic. An excellent article on this subject 
appeared in the Report of the Massachusetts Board of 
Health for 1883. The agitation of those times no doubt 
caused the manufacturers to substitute other coloring 
matters in the place of arsenical, so that at the present 
time it is very unusual to find a wall paper that contains 
arsenic. 

Experiment 16. To test for arsenic in paper * or in fabrics, 
cut the paper or green cloth into shreds, and boil this in a test 
tube, half full of water. Add to this about 10% of strong 
hydrochloric acid and a very small piece of bright copper foil. 
Boil the liquid for at least five minutes and notice if there is 
any dark coloration on the copper. When no coloration appears, 
arsenic is absent. If there is a coloration or deposit, remove 
the piece of copper carefully and wash thoroughly. Dry it 
on a piece of filter paper over a lamp and then place it in a 
matrass (a small glass tube closed at one end) and heat cau- 
tiously. If arsenic is present, there will be a sublimate of crys- 
tals of arsenious oxid (As 2 3 ) on the inside of the tube. Exam- 
ine these crystals with a lens and notice also if they reflect 
light or show triangular faces. 

INJURIOUS TRADES 

There are many trades in which the health of the work- 
men suffers from dust or injurious gases. Dr. Hirt has 
studied the effect of various trades on the health of the 
workmen in Germany. He made a particular study of 
consumption among the workmen, and gives the following 
as a list of the most injurious trades : flint cutting, 
needle and file making, lithographing, binding, brush 
making, stone cutting, grindstone cutting, type found- 
ing, cigar making, molding, glass working, dyeing, and 
weaving. The sharp mineral dust is by far the most 

1 Arsenical paper may be prepared by soaking filter paper in a solu- 
tion of sodium arsenite or in Paris green, suspended in water. 



24 SANITARY AND APPLIED CHEMISTRY 

injurious. The worst vegetable dust is cotton fiber, and 
this produces great mortality, especially among women. 
The mortality is probably increased on account of the 
high temperature and lack of ventilation in the manu- 
factories where they are obliged to work. 

GROUND AIR 

Air is contained in the ground sometimes to a depth of 
20 feet. It is forced into the ground both by its weight 
and by the pressure of strong winds. Pettenkofer found 
in 1870 that the air contained in the ground is not as pure 
as ordinary air. A comparison of dry ground air with 
ordinary dry air is given by Price. 1 

Average Composition of Atmospheric Air in 100 Volumes 

Nitrogen 79.00% 

Oxygen 20.96% 

Carbon dioxid 04% 

Average Composition of Ground Air 

Nitrogen . 79.00% 

Oxygen 10.35% 

Carbon dioxid 9.74% 

The excess of carbon dioxid is due to decay of organic 
matter that has taken place in the soil, and the decrease in 
oxygen is due to the fact that it has been used up by the 
bacteria and in various processes of oxidation. This air 
also contains a large number of bacteria, and other organic 
forms of life. When we remember that a cubic centimeter 
of earth contains from 200,000 to 1,000,000 bacteria, 
the opportunities for contamination of the ground air 
are apparent. The air of virgin soil is usually more free 

1 "Handbook of Sanitation," p. 3. 



THE ATMOSPHEEE 25 

from organic impurities than the air from the ground of 
thickly populated districts, and the difference can be 
readily understood when we consider the material which 
is liable to collect in or filter through the soil of a city. 
Fatal results have sometimes followed the breathing 
of air poisoned by the decay of organic matter. Sir 
Henry Thompson states that gravediggers have died 
while digging in the region of vaults and cemeteries. 1 If 
houses are built upon the so-called " made " land that has 
been filled in with all sorts of refuse from the city and 
from manufactories, the air that comes into the rooms is 
liable to be contaminated and to be deficient in oxygen. 
On account of the vitiation of air by decaying organic 
matter, in large cities, cremation has been quite exten- 
sively advocated and is no doubt an excellent method for 
the disposal of garbage and dead bodies. 

OFFENSIVE GASES 

In the ordinary apartment there is little danger of injury 
from poisonous gases. In the centers of trade the gases 
from some manufactories would be offensive, if they were 
taken into the lungs, but they are rapidly diffused through 
the atmosphere. Even sewer gas, which is usually con- 
sidered so dangerous, has been shown frequently to con- 
tain a less number of microorganisms than the outside air. 
This gas is, of course, disagreeable, often lacking in oxygen, 
and should by no means be allowed to escape into a 
dwelling. 

1 "Cremation," R. E. Williams, p. 44. 



CHAPTER II 

FUELS 

HISTORY 

As previously stated, fire was regarded by the ancients 
as one of the elements and a gift of the gods. Stahl, a 
German chemist, in 1697 advanced the theory that when 
anything is burned a volatile substance called " phlogis- 
ton/' which was contained in the combustible material, 
escaped. It was only after the discovery of oxygen, in 
the latter half of the eighteenth century, that the true 
theory of combustion began to be understood. Ordi- 
nary combustion is simply a combination of the combus- 
tible part of the fuel with the oxygen of the air, leaving 
nitrogen and the other gases unchanged. By this burning 
of the fuel an oxid is formed ; if carbon burns, it is the 
oxid of carbon known as carbon dioxid ; if hydrogen burns, 
it is the oxid of hydrogen known as water. 

In the production of heat for ordinary purposes, such 
fuels as wood, charcoal, peat, lignite, bituminous coal, 
cannel coal, semianthracite, anthracite, coal gas, and 
natural gas are used. Wood spirit, denatured alcohol, 
common alcohol, gasoline, and kerosene find a limited 
use; and electricity may be used for heating under 
special conditions. 

The combustible elements in these fuels are carbon and 
hydrogen, the former burning with scarcely any visible 

26 



FUELS 



27 



flame, and the latter also burning with a colorless flame. 
The calorific power of fuels, that is, the quantity of 
heat evolved by burning one gram in oxygen, differs 
greatly. 

The unit, in terms of which quantities of heat are meas- 
ured, is the calorie. A calorie is the quantity of heat re- 
quired to raise the temperature of one gram of water one 
degree centigrade. Since this quantity varies with the 
temperature of the water, it is usual to specify that the 
water shall be at 15° C. and be raised to 16° C. 

Heat values of combustibles are often given in terms of 
British Thermal Units (B.T.U.) per pound of fuel, or in 
the case of gases per cubic foot. A B. T. U. is the amount 
of heat required to raise one pound of water one degree F., 
usually from 59°-60°. The following are some of the 
more common values obtained : — 



Solid and Liquid Fuels * 



Fuel 



Calories 
per Kilo 



Btu per Lb. 



(0°C.; 760 

Mm.) Btu 

per Cu. Ft. 



Carbon to C0 2 
Lignites . . . 

Peat (average) 
Wood . . . 

Oven cokes 
Gas cokes . . 
Oil (petroleum) 



8,140 
4,000 

to 
8,000 
4,500 
3,000 

to 

6,000 

8,000 

7,800 

10,000 



14,650 

7,200 

to 

14,400 

8,100 

5,400 

to 

10,800 

14,000 

14,000 

18,000 



1 " Calorific Power of Fuels," Poole, p. 210 et seq. 



28 



SANITARY AND APPLIED CHEMISTRY 



Gaseous Fuels l 



Fuel 



Hydrogen 

Carbon monoxid .... 

Methane (Marsh gas) . . 

Acetylene 

Benzene (C 6 H 6 ) .... 
Natural gas (average value) 
Artificial gas (average value) 

Pintsch gas 

Water gas 



Calories 
per Kilo 


Btu per Lb. 


34,500 


62,100 


2,487 


4,476 


13,245 


23,851 


11,925 


21,465 


10,250 


18,450 



(0°C.; 760 

Mm.) Btu 

per Cu. Ft. 



348 

349 
1065 
1555 
4010 
1000 

600 
1320 

300 



As many combustibles contain some oxygen in addition 
to the carbon and hydrogen, in order to find the actual 
amount of heat developed, we estimate what would be 
produced from the combustion of the carbon, and of so 
much hydrogen as is in excess of that necessary to form 
water with the oxygen present in the fuel. In estimating 
the available heat produced, we must deduct from the 
total calorific power the amount of heat necessary to 
convert into steam all the water formed by the combina- 
tion of the hydrogen, and all the water originally present 
in the fuel. 

When the carbon is burned, the sole product of the com- 
bustion is carbon dioxid, thus, C + 2 = C0 2 ; but if 
the combustion is incomplete from lack of sufficient air, 
the combustion would be represented by the equation, 
2 C + 2 • = 2 CO, in which the poisonous gas, carbon mon- 
oxid, is formed at the same time as the carbon dioxid. It 
will also be seen from the above table that much less heat 
results from the burning to carbon monoxid than when the 

* Thompson's " Thermo chemie Untersuchungen." 



FUELS 29 

carbon burns completely to carbon dioxid. Smoke con- 
sists largely of unburned carbon, which might have been 
burned completely to carbon dioxid if the conditions for 
combustion had been better. 

In the burning of hydrogen, nothing but water, in the 
form of steam, is produced, thus, 2 H 2 + 2 = 2 H 2 0. In 
addition to the above products there are some others that 
are incidental, and due to impurities in the combustibles. 

The original basis of the ordinary fuels is cellulose 
(CeHioC^c, which is found in a very pure form in clean 
cotton and in pure filter paper. It is believed by geolo- 
gists that not only peat, but also the different kinds of coal, 
came originally from vegetable material. In the case of 
peat the amount of oxygen and hydrogen have not been 
so completely eliminated by the combined action of heat 
and pressure in the earth, as in the case of the soft coals 
and anthracite. 

WOOD AS FUEL 

If a fuel is porous, like" wood, so that the air can pene- 
trate into the interior, it will be readily ignited and burn 
quite freely. The ordinary practice of piling the wood 
loosely to build a fire is, of course, in accordance with this 
principle. If the fuel contains considerable hydrogen, 
especially when in the proportion to unite with oxygen, 
as in the case with wood, it is free burning. When but 
little luminous gas can be formed, as in the burning of 
charcoal, coke, or anthracite, the heat is more intense and 
concentrated at a point near the burning material. Other 
fuels, such as wood, soft coal, petroleum, etc., burn with a 
long, smoky flame, and the heat will be distributed over a 
larger flue surface. 

The experience of foresters, both in this country and 



30 SANITARY AND APPLIED CHEMISTRY 

in Europe, has shown that to be fit for fuel and economical 
for use, the softer woods must grow from twenty to thirty 
years and the harder woods from fifty to one hundred and 
twenty years. In many parts of Europe the government 
requires that the forests be renewed as often as they are 
cut, and only in this way is it possible to keep the supply 
of fuel and timber intact. The preservation of forests 
also tends to keep the moisture in the soil, so that the 
streams shall not dry up in summer and there will not be 
the liability to sudden floods that there is in regions from 
which the timber has been cut. 

There is more water in wood that is cut in the spring 
than if it is cut in January, and there is more in the young 
twigs and stems than in older wood. Different varieties 
of freshly cut wood contain the following per cent of 
water : — 

Willow 26.0% Aspen 43.7% 

Sycamore 27.0% Elm ...... 44.5% 

Birch 30.8% Fir 45.2% 

Oak 34.7% Larch 48.6% 

Pine 39.7% White Poplar . . . 50.6% 

Beech 39.7% 

One and a half to two years after being cut wood gets as 
dry as it can by simple exposure to the air, and it is called 
" seasoned " or " air dried/ ' but it still contains from 20 % 
to 25 % of moisture. 

Wood several years old, kept in a warm room, may still 
retain 17 % of moisture. Wood may be kiln-dried, and in 
this process will lose from 16 % to 20 % of moisture. If 
the air is expelled from wood, it is sensibly heavier than 
water, and the specific gravity is from 1.30 to 1.50. On ac- 
count of being heavier than water, " water-soaked " wood, 
or that in which all the air has been replaced by water, 
will of course sink to the bottom of a stream. 



FUELS 31 

The amount of moisture in wood is of great importance, 
because of the large amount of heat that is used up in its 
evaporation when burning ; and so it goes without saying 
that dry wood is more economical than green wood. Res- 
inous woods, such as fir, spruce, and pine, have an in- 
creased heating value on account of the pitch and resinous 
gums which they contain. 

The best woods to use for fuel are the hard woods such 
as hickory, oak, maple, and beech. These burn slowly 
and have great heating value. 

The amount of ash in wood differs greatly as it is made 
from old or young wood and from the whole wood or the 
bark. Willow wood contains 2% of ash; oak, 1.65%; 
beech, 1.06%; Scotch fir, 1.04%); birch, 0.85%. This 
ash consists essentially of sodium and potassium carbon- 
ates, calcium and magnesium carbonates, with some phos- 
phates, sulfates, and silica (see Soap, p. 128). 

CHARCOAL 

When wood is heated in a limited supply of air, a kind of 
distillation takes place, and the residue that is left is called 
charcoal. The ordinary method of charcoal making has 
been to pile the wood and cover with turf or soil, and then 
apply a flame to the center of the pile and allow a little air 
to enter the bottom so that the combustion shall go on 
slowly. This process requires several weeks, and no at- 
tempt is made to utilize any of the valuable constituents 
in the smoke and gas given off. 

Charring in kilns has more recently been resorted to, and 
here the products of combustion are utilized. The wood is 
placed in a brick kiln, which is heated by the combustible 
gases given off from other furnaces of the same battery. 
The smoke and other products of combustion are drawn 



32 SANITARY AND APPLIED CHEMISTRY 

out of the kiln by fans, through a series of condensers, 
where the wood alcohol, tar, and crude acetic acid are 
deposited, and afterward purified for the market. About 
27 % of charcoal is the yield by this process, while only 20 % 
is produced by the charcoal pit process. 

PEAT 

This fuel is very slowly formed, especially in shallow 
pools, by the decomposition of vegetable matter. The 
peasants in Great Britain, Northern Germany, Holland, 
and some other countries cut the peat or " turf," as it is 
sometimes called, into cubical blocks and pile it on plat- 
forms to dry. As it often contains as much as 45 % of 
water, it is important that the drying should be thor- 
oughly done, or in burning but little heat will be obtained. 
It is, of course, a cheap fuel and burns with a smoky 
flame. 

A peat bog is composed of the various mosses and sedges 
that grow so readily in damp ground and die at the end of 
the season, to be succeeded by similar vegetation the next 
season. Sometimes trunks of trees are found in it and even 
animal remains. Peat contains about 16 % of water and 
41 % of fixed carbon. 

It is estimated that there are in Great Britain 6,000,000 
acres of peat swamps, and that each acre would yield 1000 
tons of peat charcoal. In Ireland one seventh of the whole 
island, or 2,830,000 acres, is peat bog. The value of peat 
depends on its dryness, density, and firmness. Peat leaves 
from 8% to 12% of ash. 

COAL 

Lignite or brown coal is intermediate between peat and 
ordinary soft coal in composition, and is of more recent for- 



FUELS 33 

mation than the latter. Although it burns freely, it con- 
tains from 15 % to 20 % of moisture, and leaves quite a 
large amount of ash. 

Cannel coal is a peculiar variety of coal, having a con- 
choidal fracture like broken glass, and only a slight luster. 
The name comes from the Scotch pronunciation of the 
word " candle/' and refers to the fact that splinters of this 
coal will burn like a candle. Cannel coal is especially 
valuable for making illuminating gas, as it yields a large 
quantity per ton. 

Bituminous coal is very widely distributed in most 
countries of the world. Some of these coals burn with a 
smoky flame, and " cake/' or form a coke which is hard 
and seems to fuse together, while others are " non- 
caking/ ' and burn freely, with little smoke, to an ash. 
The latter are well adapted for domestic use. In the 
use of an oven that is heated with a fire on the outside, 
the former is a cheap and satisfactory fuel, except for the 
abundance of smoke which it gives off. 

Semibituminous coals are found in several localities, but 
particularly from Pennsylvania across the southern bound- 
ary of Virginia into Tennessee. The volatile matter ranges 
from 12 % to 25 %, and this combustible portion is quite 
uniform in composition. 

The semianthracite coals, like the Eureka and Ouita of 
Arkansas, burn freely, with but little flame, and show a 
tendency to decrepitate and fall through the grate. 

Anthracite coal occurs only in a few localities, but 
sometimes in veins forty feet in thickness. It has a high 
luster, and a specific gravity of about 1.75. It burns 
with little flame and smoke, and is admirably adapted for 
domestic use, as the heat is concentrated and intense 
directly over the fire rather than distributed through a 



34 



SANITARY AND APPLIED CHEMISTRY 



long flue as when soft coal burns. When a naked fire is 
used for baking, as in a large cracker bakery, anthracite 
or coke is a very satisfactory fuel. 

Coke, the material left in the retort after gas has been 
made from soft coal (see p. 62), is quite a bulky fuel, 
and leaves considerable ash. It is also made in " bee 
hive " coke ovens, and the distillation products are allowed 
to escape. " By-product " coke ovens are coming into use 
to save the very valuable substances such as ammonia 
and coal-tar products found in the gases and smoke. 

Briquettes are being used to save the waste both in this 
country and abroad. They are made by compressing 
with tarry matter, in a suitable mold, the powdered coal 
that is formed in preparing the product for market. 

Petroleum coke is left in the retorts after all the volatile 
constituents have been driven off from the oil. It is a 
clean, porous product and an excellent fuel for domestic 
purposes. 

Analysis of Various Coals 





Water 


Volatile and 

Combustible 

Matters 


Fixed 
Carbon 


Ash 


Lignite 

Semibituminous, Pa. 1 
Bituminous, Pa. 1 
Cannel 




18.00 
0.81 
1.97 
undet. 
6.47 
. 1.11 
3.09 


20.90 
21.10 
38.60 
37.20 
38.82 
12.73 
4.28 


50.90 
74.08 
54.15 
61.60 
49.10 
77.62 
83.81 


10.20 
3.36 
4.10 
1.20 


Canon City, Colo. . 
Semianthracite, Ark. 
Anthracite 1 . . . 




5.61 
8.56 
8.18 



The greater the amount of moisture the less valuable the 
coal, as in the case of wood. The " volatile and com- 

1 Trans. A. I. M. E. 



FUELS 35 

bustible " matter referred to in the table is that which 
goes off when the coal is heated in a closed vessel. 
It is this which gives the smoky flame to bituminous 
coal. Fixed carbon is the coke, which finally burns 
with little flame and leaves a residue of ash. It will be 
noticed that there is a regular decrease in volatile matter, 
from the bituminous coal to the anthracite, and a corre- 
sponding increase in fixed carbon. 

COAL AND COKE 

Experiment 17. Heat to a high temperature over a blast 
lamp as long as any smoke is given off about 2 g. of pulverized 
"coking" bituminous coal in a platinum or porcelain crucible 
closely covered. When the cover is removed, the mass of 
coke will be found in the crucible. This, less the ash which 
would remain on complete combustion in the air, constitutes 
the " fixed carbon " referred to above. 

In many localities where there is no local supply of coal, 
there is a direct relation between the retail cost of different 
kinds of coal and the amount of fixed carbon which they con- 
tain, — the greater the per cent of fixed carbon, the higher the 
price. 

Experiment 18. Compare the retail price of different 
kinds of coal, as anthracite, semianthracite, bituminous, etc., 
and the composition as given on page 34. 

GAS AS FUEL 

Natural and artificial gas are both important fuels, even 
for domestic use. Natural gas has been in use on a small 
scale for a number of years, but it was not until about 1880 
that it became of commercial importance in the United 
States. It is now obtained in quite large quantities in 
Pennsylvania, New York, West Virginia, Ohio, Indiana, 
Kentucky, Texas, and Kansas. The method of boring the 



36 SANITARY AND APPLIED CHEMISTRY 

well is to use what is called a churn drill, which pulverizes 
the rock, and the borings may then be washed out with a 
stream of water. 

The hole, which is from 4 to 6 in. in diameter, is usually 
cased with iron pipe as the drilling progresses, but the cas- 
ing is smaller nearer the bottom. The depth is usually 
from 300 to 1600 feet. The gas occurs in what is called a 
" gas sand/' which is often quite thick. The pressure of 
the gas is frequently from 300 to 400 lb. per square inch, 
so that it is with great difficulty held in check. The gas 
is often conveyed in pipes for hundreds of miles, in which 
case powerful pumps are used to force the gas through the 
pipes and finally, by regulators, the pressure is reduced 
for domestic consumption so that it shall be burned at 
from 4 to 12 inches of water pressure. 

A cheap fuel gas can be made in some sections at a low 
price, and will, it is hoped, supersede the use of coal for 
cooking and heating in large towns and cities where natural 
gas cannot be obtained. The advantages of burning gas 
over any other fuel are obvious, for it is immediately avail- 
able to warm a room or cook a meal, and there is no waste 
of fuel, when the occasion for its use is past. There is 
no dust, ashes, or smoke, and the products of combustion 
can be carried out of the room by a very small pipe. 
These products should, however, always be removed, for, if 
allowed to accumulate, the carbon dioxid and other gases 
make the air of the room decidedly impure. The gas stove 
does not heat the room unnecessarily as does a coal stove, 
and gas is a perfectly safe fuel, which is more than can be 
said of gasoline as ordinarily used. 

The burners used in heating by gas are all made on the 
principle of the Bunsen burner. The proper amount of air 
is allowed to enter at the bottom of the tube or, in the 



FUELS 



37 



large burners, through the " mixer.' ' The burner that 
is put into a cook stove, for instance, can be made of a 
piece of two-inch gas pipe capped at one end and having 
three rows of small holes drilled in the top from one end to 
a point near the other. The " mixer " is screwed on at the 
end through which the gas is admitted. There is little 
danger in the use of natural gas if ordinary precautions are 
taken. There is, of course, a possibility that the pressure 
may change so that the gas may go out at night, but this 
is not often the case with the present methods of regulating 
the supply. It is true that there are some cases of suffoca- 
tion from the careless use of natural gas, but it is not as 
poisonous as coal gas or " water gas" (see Lighting, p. 63). 
The composition of natural gas from different localities 
is as follows : — 



Ohio 


Indiana 


Kansas * 


.3 


.25 


.44 


.5 


.45 


.33 


92.6 


92.67 


95.28 


3.5 


3.53 


3.28 


.3 


.35 


— 


2.3 


2.35 


— 


.2 


.15 


— 


.3 


.25 


.67 



Russia 



Carbon dioxid . 
Carbon monoxid 
Marsh gas . . 
Nitrogen . . . 
Oxygen . . . 
Hydrogen 2 . . 
Hydrogen sulfid 
Olefiant gas, etc. 



.95 

92.49 
2.13 

.94 

4.11 



The preparation and properties of illuminating gas are 
discussed under Lighting, p. 62. 

Gasoline, one of the products from the distillation of 
petroleum, which is so extensively used as a fuel for cook- 

1 This gas has a "B. T. U." (British Thermal Unit) value of 920, 
as ordinarily computed. 

2 By recent methods of analysis, natural gas is usually found to be 
practically free from hydrogen. 



38 SANITARY AND APPLIED CHEMISTRY 

ing in some localities, is burned in stoves so constructed 
that the liquid is converted into vapor by the heat of the 
burner before it is burned, and it is also mixed with suffi- 
cient air so as to burn completely with a blue flame, which 
does not deposit soot on the cooking utensils. 

The chief danger in the use of gasoline is due to the fact 
that it gives off a volatile vapor, even at ordinary tempera- 
ture. The vapor of gasoline is not only extremely com- 
bustible, but when mixed with a certain proportion of air 
it is highly explosive. Gasoline stoves are usually so 
constructed that the tank which holds the liquid is at 
some distance from the flame and it should never be 
filled without first extinguishing the flame. 

Kerosene is often used as a fuel for heating and cooking. 
As at present burned in stoves of special construction it is 
very satisfactory. There is danger of smoking unless the 
wick is carefully trimmed. The products of combustion 
should always be carried away by a suitable flue, as they 
are both disagreeable and injurious to health. 

Wood alcohol, known also as methyl alcohol, is often 
used for heating chafing dishes, coffee percolators, etc. 
It has three fourths the heating value of ordinary alcohol 
or " grain spirits. " Grain alcohol which is " denatured " 
by adding to it some substance that renders it unpalatable, 
is an excellent fuel to use for small fires. 



CHAPTER III 

HEATING AND VENTILATION 

HEATING 

These two subjects are so intimately associated that one 
cannot be considered without the other, and one system 
should be installed at the same time as the other. 

The common methods of heating are through — 

(1) Direct radiation. 

(2) Indirect radiation. 

(3) Direct-indirect radiation. 

The means of obtaining the heat are : — 

By the fireplace or open grate. 

By stoves. 

By hot-air furnaces. 

By steam with direct radiation. 

By steam with indirect radiation. 

By hot water with direct radiation. 

By hot water with indirect radiation. 

By electricity. 

Direct radiation includes the use of a fireplace or open 
grate, which, however satisfactory it is in the way of ventila- 
tion and for imparting cheerfulness to a room, is not an 
economical method of heating, because it wastes from 75 % 
to 90 % of the fuel. The fireplace, where only the radiant 
heat was utilized, was the primitive method of heating 

39 



40 SANITARY AND APPLIED CHEMISTRY 

dwellings when fuel was not expensive. Many devices 
have been proposed for making the fireplace more efficient. 
Among them may be mentioned the ventilating grate, in 
which air is brought from outside and heated by passing 
back of the fire and then comes into the room through 
gratings above the fireplace. The Franklin stove, in- 
vented by Benjamin Franklin when placed partly within 
the room, is an illustration of heating by a combination 
of the radiation and convection methods. One of the 
chief reasons why people take cold so easily is that they 
work, eat, and sleep in rooms that are heated to a high 
temperature, with little moisture, and where no attention 
is paid to ventilation. The fireplace, which was univer- 
sally used less than seventy-five years ago, furnished pure 
air, although the heat of the room was badly distributed. 

Under the head of direct radiation may also be included 
the heating by stoves, or by pipes or radiators carrying 
steam or hot water. When the room is heated by a stove, 
as air is necessary for the combustion of the fuel, and there- 
fore is removed from the room through the chimney, an 
equivalent amount must enter the rooms through the 
cracks around the doors and windows. This affords 
some ventilation, but not enough for rooms in which a 
number of persons are assembled. Direct radiation sys- 
tems are cheaper in construction and, with the exception 
of the open grate or fireplace, do not use as much fuel as 
indirect systems. 

When rooms are heated by a stove, there is no reason 
why air cannot be brought in from the outside beneath 
the stove, and pass over it to become heated, and then into 
the room. By this means fresh air will find its way into 
a room, and there is little difficulty in removing air from a 
room, especially if it is warm or under a little pressure. 



HEATING AND VENTILATION 41 

In the use of the stove for heating, it should be large 
enough to thoroughly heat the room, even in the coldest 
weather, without running it at its fullest heating capacity, 
for it is not economy to heat a room with a small radiating 
surface. The air of the room that is in contact with this 
surface becomes overheated. Stoves heat a room largely 
by convection, that is, by heating the air that is directly 
in contact with the stove, and when this becomes heated, 
it rises and gives place to colder air. 

The openings at the bottom of a stove or furnace should 
be so arranged as to completely shut out the air if neces- 
sary, and thus control the fire. This is much safer than 
the practice of shutting the damper in the pipe, as this 
will often drive the products of the combustion into the 
room; this might occur during the night, especially if 
the wind dies down, and the suffocating carbon dioxid and 
sulfur dioxid, as well as the more dangerous carbon 
monoxid, would be driven into the room. When sufficient 
air for complete combustion is not admitted below the 
fire, more carbon monoxid will result, and the full heating 
value of the fuel will not be obtained. — These conditions 
are represented by the equations — 

C + 2 = C0 2 , 

and in the upper part of the fire pot — 

C0 2 + C = 2 CO. 

THE HOT-AIR FURNACE 

Indirect radiation may be secured in the simplest way 
by the use of the ordinary hot-air furnace. Here air is 
brought from the outside and passes over the heated 
surface of the iron, and is then admitted to the room. If, 



42 SANITARY AND APPLIED CHEMISTRY 

in addition to this, open grates or fireplaces are used, the 
heating is nearly uniform and the ventilation is satis- 
factory. 

If a building is heated by a furnace, great care should be 
taken that the air that comes into the room is from out of 
doors and not from the cellar. The danger of ground air 
has been spoken of (p. 24), and this danger is still greater 
if it is contaminated with the gases that arise from 
decayed vegetables in the cellar. The amount of air 
coming into the furnace can be regulated if it is brought 
in from outside, and an excess, or more of the cold air 
than is thoroughly heated, can be avoided. If there is 
not enough air, the flues of the furnace are liable to be- 
come overheated, and the furnace will thus be damaged, 
and the air that does come in under these conditions will 
also be liable to contain carbon monoxid (see p. 15) and 
on this account be poisonous. The opening for the ad- 
mission of fresh air should be so arranged that the winds 
will not seriously affect the amount of air admitted. 

It is a common practice to take the air from the living 
rooms and the hall of the dwelling and return it over the 
furnace, thus using the same air over and over again. 
While this is no doubt economical, as far as expense of 
fuel is concerned, a part of the air at least should be taken 
from out of doors, and air should be reheated only in the 
coldest weather, and for warming the house in the morning. 

There should always be some arrangement for adding 
moisture to air that is heated, as the capacity of heated air 
for taking up moisture is greatly increased (see p. 7) ; 
if moisture is not supplied, unpleasant sensations from the 
apparent dryness of the air are produced and there is 
greater liability to take cold. Pans of water are placed 
in the hot-air chamber of a furnace to allow the moisture 



A 



HEATING AND VENTILATION 43 

to evaporate and mix with the air which enters the room. 
An ordinary furnace will evaporate at least three gallons 
a day, in cold weather. 

STEAM HEAT 

In the use of steam with indirect radiation, it is conven- 
ient to have steam coils in the lower part of the building 
so situated that fresh air can pass over them, and then 
through suitable flues into the rooms above. Here again 
some provision can be made to keep the incoming air 
moist, by placing pans of water upon the steam coils. 

Steam is generally used under a pressure below twenty 
pounds per square inch, so the temperature is not very 
much above 100° C. (212° F.), or " exhaust " steam from 
an engine may be used. In some systems high-pressure 
steam is employed, and in this case the temperature of 
the radiators is considerably above 100° C. If direct 
radiation is used, one disadvantage of this method of 
heating is that the air in the room is dry. In order to 
obtain heat from the steam, it must be condensed in the 
radiator, so there must be an opportunity for the water to 
run back freely to the boiler or to a steam trap. 

HOT-WATER HEATERS 

Water is used for heating on account of its great capacity 
for retaining heat. The hot water can be carried in pipes 
to some distance from the boiler, give up its heat, and 
then be returned by another series of pipes to the boiler. 
The water in the system may be under pressure, but it is 
usually carried in an open system, with a small tank at the 
top of the building, which is filled occasionally to supply 
the waste of evaporation or leakage ; and vents must be 



44 SANITARY AND APPLIED CHEMISTRY 

provided to allow the air that is dissolved in the water to 
escape. Under these conditions the hot water from the 
boiler in the cellar flows upward through the pipes and 
radiators and warms the building, and the heavier cold 
water runs back to the boiler and enters at the bottom 
through another set of pipes, and the heat keeps the water 
circulating. It should be noted that the difference in 
weight between the column of hot water and that of cold 
water is what keeps up the circulation in the system. 

The hot-water system has this advantage over steam 
that as soon as the water is warm enough to circulate it 
begins to warm the room, and the heat is retained for a 
long time after the fire has been allowed to die down. In 
the case of steam there is no heat from the radiator till 
the water in the boiler is above the boiling point. With 
the use of hot water the temperature of the radiator is 
never above 100° C. and usually much below this, and 
with a suitable surface for evaporating water in the rooms 
the air will be agreeable. As the temperature of the 
radiating surface is lower than in the case of steam, the 
heating surface must be much larger, and so it is more 
expensive to install a hot-water system. This is no doubt 
the chief reason why it is not more generally used, and 
added to this is the greater liability to leaks, and the danger 
from freezing if not handled with care. 

In the direct-indirect method of heating, air is brought 
from the outside behind or below a steam or hot-water 
radiator standing in the room, and is heated in its passage 
over the radiator. This is also theoretically very satisfac- 
tory, as good ventilation is secured, though it is not often 
attempted on a large scale. 



HEATING AND VENTILATION 45 

ELECTRIC HEATING 

At the present cost of electricity, it is not extensively 
used for heating, except in the case of street cars and 
small offices. With the increased use of water power to 
produce electricity, the use of this heating agent will no 
doubt soon be much more common. The use of electrical 
cooking devices is already quite large. They are especially 
adapted to small apartments, or rooms where there is extra 
danger from fire. One great advantage of the use of 
electricity over that of stoves is that the air of the room 
is not vitiated by electricity. 

VENTILATION 

But little attention is paid to ventilation by people in 
general, because they do not appreciate the injury to the 
body, as it is so gradual. The evil effect of bad air can be 
readily shown by the study of the health of those who are 
confined in close, badly ventilated barracks or tenements, 
or of workmen in crowded factories. Even domestic ani- 
mals thrive much better in fight, clean, well-ventilated 
stables. Consumption in some form is often the result of 
living in close, badly ventilated rooms. A practical demon- 
stration of the fact that pure air is inimical to the growth of 
the bacilli that cause consumption is shown in the recent 
methods of treating this disease by requiring patients to 
live out of doors throughout the entire year, and in the 
establishment of sanatoria in elevated regions, where an 
abundance of fresh air is the most important part of the 
treatment. 

Many public buildings have no provision for ventilation 
during that part of the year when they must be heated, and 
this is the case even with those buildings that are intended 



46 SANITARY AND APPLIED CHEMISTRY 

to accommodate large audiences. There is a great want of 
appreciation of the necessity for ventilation, so that house 
renters never think of making any inquiry as to whether 
any facilities for ventilation exist or not. In many schools 
and assembly rooms there is no provision for ventilation 
except by opening windows and subjecting the audience to 
a dangerous draft. One reason for this, no doubt, is that 
we do not notice that air is impure until it is extremely 
impure. We suffer great discomfort, especially from high 
temperature, and then think that we need fresh air. 

It is estimated that the daily respiration of each indi- 
vidual is 346 cu. ft., 1 and the amount of carbon dioxid 
given off from the lungs in the same time is 16.25 cu. ft. 
It might seem that carbon dioxid that is produced by the 
combustion of oil and of gas and in the process of respira- 
tion, since it is heavier than the air, would sink to the 
bottom of the room, and remain there ; but the fact is that 
an analysis of the air will show that on account of the dif- 
fusion of gases, the gas in question will be nearly uniformly 
distributed throughout the room. To such an extent is 
this the case that we expect to find greater discomfort in 
the gallery of a crowded hall than on the first floor, since 
the expired air being warmer tends to rise, notwithstanding 
its greater content of carbon dioxid gas. 

The air of overcrowded, poorly ventilated rooms, as a 
result of life processes, is altered as follows : — 

" There is a slight diminution in the amount of oxygen ; 
there is an increase in the amount of carbon dioxid along 
with the organic pollution, resulting from the decomposi- 
tion of perspiration and epithelium on the surface of the 
body, and from gastric and intestinal digestion and de- 
composition ; and there is a slight elevation of tempera- 

1 J. S. Billings, "Ventilation and Heating," p. 88. 



HEATING AND VENTILATION 47 

ture and addition of moisture. In the impure air there 
are more solid particles often organic upon which may be 
deposited either innocent or disease-producing bacteria, 
for the most part the former/' 

A prominent author, 1 in speaking of this " crowd poison- 
ing/ ' as it may be named, calls attention to the fact that it 
induces a general lowering of the vital processes, impair- 
ment of nutrition, and loss of muscular strength ; the blood 
becomes laden with effete matters from diminished aera- 
tion; a craving for alcoholic stimulants follows on the 
nervous depression; and the subjects of this poisoning 
fall easy victims to disease. The prevalence of " con- 
sumption " among those workmen whose time is passed 
largely in badly ventilated and crowded shops, which was 
formerly charged to the use of "rebreathed " air, is now 
believed to be only remotely chargeable to these condi- 
tions ; for the conditions produce lowered vitality and 
less resistance to infection by spores of disease, which may 
be inhaled with the dust, either in the workrooms or 
elsewhere. 

After all that has been said, as noted in the previous 
paragraphs, about the history of our investigations on 
the cause of the disagreeable effects produced by breath- 
ing impure air, the consensus of opinion at the present 
time seems to be that " wherever in closed, crowded 
rooms certain impairment of health ensues, such as head- 
ache, dizziness, nausea, etc., these symptoms are to be 
attributed solely to heat retention." 2 Overheating seems 
to be the chief evil to be guarded against in the ventila- 
tion of the schoolroom or the home, and at the same time 
the air should be supplied with a sufficient quantity of 

1 Willoughby, "Hygiene for Students," p. 166. 

2 Baskerville, Journal of Ind. and Eng. Chern., Vol. VI, p. 250. 



48 SANITARY AND APPLIED CHEMISTRY 

moisture. Much of the inconvenience will be remedied 
if the air is not allowed to stagnate around the body. If in 
motion it will remove the excess of heat from the surface. 
No doubt one of the chief reasons why the sleeping porch 
has been found to be so advantageous is that these condi- 
tions do not allow a stagnation of air in the vicinity of 
the body. 

Of the impurities mentioned, the carbon dioxid, which in 
moderate quantities is not poisonous, is the most readily 
determined as an index of the impurity of the air, so special 
attention is given to this substance (see p. 12). 

Another source of contamination in a living room, which 
should not be neglected when the room is artificially 
lighted, is the products from the combustion of illuminat- 
ing gas, oil, or candles. This not only decreases the per 
cent of oxygen and increases the per cent of carbon dioxid 
in the air, but it introduces other gases, such as sulfur 
dioxid and ammonium compounds. Ordinary burners 
use from 3 to 6 cu. ft. of gas per hour, and so in a large 
room there would be required from 1500 to 5000 cu. 
ft. of air per hour to properly dilute the products of 
combustion. 

According to Parkes, 1 the amount of fresh air to be sup- 
plied in health during repose ought to be : — 

For adult males, 3600 cu. ft. per hour for each person. 
For adult females, 3000 cu. ft. per hour for each person. 
For children, 2000 cu. ft. per hour for each person. 

The following may be considered as a conservative esti- 
mate of the amount of air required in buildings of ordinary 
construction : 2 — 

1 "Text Book of Human Physiology." 

2 J. S. Billings, "Ventilation and Heating," p. 129. 



HEATING AND VENTILATION 49 

Cubic Feet of Air per Hour 

Hospitals . 3600 per bed. 

Legislative assembly halls 3600 per seat. 

Barracks, bedrooms, and workshops . . 3000 per person. 

Schools and churches 2400 per person. 

Theaters and audience halls 2000 per seat. 

Office rooms 1800 per person. 

Water closets and bath rooms .... 2400 each. 

Dining rooms 1800 per person. 

Those who are taking moderate exercise need one and 
one half times as much air, and during violent exercise 
three times as much air, as when at rest. 

These amounts of air are much larger than those given 
by Morrin, the French writer, but in view of the contami- 
nation of indoor air from various sources, they do not 
seem to be too large. In the Boston Theater 50 cu. ft. 
per minute per capita is furnished. Pettenkofer says the 
amount of air should be from 23 to 28 cu. ft. per minute. 
Dr. Billings, 1 an authority on this subject, says that for 
audience halls 30 cu. ft. of air is necessary, and in legisla- 
tive buildings the apparatus should be such that at least 
45 cu. ft. of air per person per minute can be furnished, 
with a possibility of increasing to 60 cu. ft. At the Vienna 
Opera House, which is considered one of the best-ventilated 
buildings in the world, 15 cu. ft. of air per minute per capita 
is supplied. 

In order to have good ventilation, the fresh air intro- 
duced into the room must be ample in volume ; it must 
be free from contamination with dust and germs. It 
must be warmed in cold weather, and, if possible, cooled 
in warm weather, and it must be introduced so as not to 
cause a draft. There should be a sufficient quantity of 
air, so that the amount of carbon dioxid in the air at any 

1 Loc. cit., p. 128. 
E 



50 SANITARY AND APPLIED CHEMISTRY 

time shall not be above six parts per ten thousand. Many 
buildings are now ventilated by drawing out the air, 
washing and purifying it and returning it to the rooms. 

The ventilation may be downward or upward, and both 
of these methods have their advocates. The disadvantage 
of upward ventilation is that the heated air of the room is 
carried off very rapidly, thus increasing largely the cost of 
heating. Greater economy of heating is secured by draw- 
ing out the impure air from a point near the bottom of 
the room. If drawn off at the top, the heat does not diffuse 
throughout the room, and the floor is liable to be cold. 
The disadvantage of downward ventilation (that is, taking 
the impure air out at the bottom of the room) is that it is 
sometimes difficult to get the currents of air to move in 
this direction. The Chicago Auditorium, however, is ven- 
tilated in this way ; 10,000,000 cu. ft. of air per hour is 
furnished, with a velocity of 1 ft. per second. The air is 
changed from 4| to 5 times per hour. This result 
is brought about by the use of four blowers to force air 
into the room, and three exhaust fans to take it out. 

In general, it may be said that ventilation may be accom- 
plished by natural draft or by a forced draft. The air may 
be forced into a room, and allowed to find its way out by 
flues, or it may be allowed to find its way into the room 
through the cracks, and be taken out by an exhaust fan. 
It is, however, greater economy of power to force air into 
a room than to draw it out by an exhaust fan. In some 
large chemical laboratories the tempered air is blown into 
the room by means of a fan, and then is carried out with a 
good draft by flues connected with hoods in the walls. 1 

As previously intimated, the most complete systems use 
both pressure blowers and exhaust fans. In some hospi- 

1 See also "A Text Book of Hygiene," Rohe and Robin, pp. 38-42. 



HEATING AND VENTILATION 51 

tals (and in these buildings, if anywhere, pure air is neces- 
sary) the air is introduced through a perforated cornice 
at the top of the room, and is then drawn out a short dis- 
tance above the floor through flues which are ventilated 
by exhaust fans. 

Where there is no other way of securing a movement of a 
current of air, it is possible to cause the air to rise rapidly 
in flues at the side of the room, by having a gas jet or some 
source of heat in the flue. The best place for this is just 
above the openings, but these flues should be much larger 
than those usually provided. A system of down draft 
that works with more or less success, has been in use in 
school buildings for many years. In this case a fire is 
kept burning in the furnace, so as to assist in the removal 
of the foul air from the rooms and from the flues. Toilets 
are often ventilated through the furnace stack by this 
system. 

When the pressure blower system is used, the air is 
drawn over the steam pipes in the winter (see p. 43), and 
it may be cooled by passing over refrigerating pipes, 
through which cold brine is circulated, in the summer. 
The air is sprayed before it enters the room to remove 
dust or smoke, or the dry air may be filtered through 
cotton or cheese cloth, in a long flue. 

If large halls are lighted by gas, the burners should be 
placed outside the room, thus allowing the light to shine 
into the room through a glass dome. This avoids heating 
the room, and the products of combustion do not in this 
way contaminate the air. Much of the foul air of the 
room will escape also at the same time if openings are left 
in the ceiling near the place where the gas is burned. 

Open grates may be used in connection with furnace or 
radiator heat to ventilate the ordinary dwelling. If stoves 



52 SANITARY AND APPLIED CHEMISTRY 

are used in closed rooms, cold air from outside may be 
brought in below the stove, allowed to pass over it, and 
a flue may be provided near the floor for the escape of foul 
air, thus securing ventilation (see p. 41). 

Various other devices have been suggested to ventilate 
an ordinary room. One of these is to bore gimlet holes in 
the walls ; these are so small that the air cannot cause a 
draft, and yet they will admit a large amount of fresh 
air. An excellent plan, and one that can be easily adopted 
in any schoolroom, is to raise the lower sash and place a 
board about 5 in. wide below it, and then air will be ad- 
mitted into the room between the two sashes and directed 
upward, so there will be no direct currents. A strip of 
plate glass is used in a similar way. This is so arranged 
that the air enters the room below the lower sash, as well 
as between the sashes. One disadvantage of opening 
the windows at the top is that the air may pass to the 
opposite side of the room, so those persons farthest away 
from the window will feel the draft, while those near by 
will not notice it. 

The air in a well-ventilated room should be in motion, 
but this motion should not be over 3 or 4 ft. per second, 
for otherwise it becomes a "draft." The ordinary dwell- 
ing fortunately affords numerous openings where air 
from outside can enter, if the air within the room is re- 
moved by a chimney or a heated flue. 

TESTING AIR 

Experiment 19. Test for currents of air at the bottom and 
top of a room by the use of thistledown or a candle flame. 

Experiment 20. Test the temperature at the top and bottom 
of a room, and in different localities. 



HEATING AND VENTILATION 53 

Experiment 21. Test for the moisture in both a cold and 
a warm room by the use of the hygrometer. 

Experiment 22. A " household test " for air, devised by 
Angus Smith, 1 is to place J oz. of clear limewater in a 10J oz. 
bottle containing the air to be tested for carbon dioxid, cork it 
tightly, and if, on shaking, there is no precipitate, the air con- 
tains less than .06 % of this gas, and is, therefore, fairly pure. 

See Experiments 10 and 11 under Air. 

1 Kenwood, "Public Health Laboratory Work," p. 203. 



CHAPTER IV 

LIGHTING 

We may properly consider that there are two kinds of 
light, natural and artificial. The most common methods 
of obtaining artificial light are by — 

(1) Combustion. 

(2) Chemical action. 

(3) Phosphorescence. 

(4) Electricity. 

To obtain light, the body, if a solid, must be heated to 
incandescence, or if a gas it must be heated till it glows. 
A carbon filament, heated to incandescence in a vacuum, 
as in the incandescent electric light, is a familiar instance 
of this class of illumination. Again, by means of the 
oxyhydrogen blow-pipe, calcium oxid is heated to a white 
heat; and when magnesium is burned, the intense light 
is due to the incandescent particles of magnesium oxid. 
When charcoal is burned, the carbon is not hot enough 
to be a source of light, but only of heat. When wood is 
burned, although the wood itself does not volatilize, there 
are certain volatile hydrocarbons given off, and these have 
the property of becoming incandescent or the carbon in 
them does so, and thus light is obtained from the burning 
wood. 

Ordinary light-producing substances may be divided 

54 



LIGHTING 55 

into solid, liquid, and gaseous. It is, however, the gaseous 
substance in either case that burns and gives the light. 
In the solid candle, for instance, the fat of the candle is 
melted by the heat radiated from the flame and becomes 
a liquid oil, and is then drawn up by capillarity into the 
wick, where a kind of distillation takes place and the oil 
is made into a gas which will burn. When any oil or 
liquid substance is burned in a lamp, it is already in a 
condition to be drawn up by capillarity, and is then 
volatilized as before. Illuminating gas is, however, de- 
livered at the burner in a condition to be burned directly 
without any previous distillation, as that has already 
been done at the gas works. 

The ordinary candle flame illustrates very well the 
theory of combustion. It is divided into three zones : 
an inner zone of unburned gas ; a middle zone, where 
partial combustion takes place; and a third or outer 
zone of complete combustion, where there is very little 
light but much heat. It is in the second zone that the 
illumination takes place; here the carbon becomes 
incandescent or white-hot. The products of combustion 
are carbonic anhydrid and water, and as both these gases 
are transparent, they do not prevent the light from radi- 
ating outward. We are indebted to Michael Faraday 
for making a very thorough study of the nature of flame 
as long ago as 1835. In the candle flame the hottest point 
is at the end of the inner zone, and the interior of the 
flame is unburned gas. 

Experiment 23. Press down into a candle flame, for an 
instant only, a sheet of white paper, and notice the ring of 
carbon deposited on it. In a similar way a ring of carbon may 
be deposited on a piece of glass, and the dark center of the 
candle can be seen on looking down inside the ring. 



56 SANITARY AND APPLIED CHEMISTRY 

Experiment 24. Blow out the flame of a candle that is 
burning with a long wick, and after an instant relight the smoke 
at a little distance from the end of the wick. The distillation 
of gas proceeds for some time after the candle is extinguished. 

COMBUSTION OF GAS 

Ordinary illuminating gas may be burned in the bat- 
wing or fish-tail burner to produce light ; or in the Bunsen 
burner, where there is enough air admitted into the bot- 
tom of the burner and mixed with the gas to give complete 
and rapid combustion, and consequently very little light. 

EARLY ILLUMINATING DEVICES 

The earliest device for obtaining light was perhaps the 
pine knot or the torch, and this was followed by the rush- 
light, and the link, which was a rope saturated with pitch. 
After this came a crude lamp made by allowing a wick to 
fall over the edge of a dish containing some liquid fat 
and then a lamp in which the wick came through the 
hole in the side of the vessel or in the lip. There are 
many very beautiful lamps of these types found in ancient 
ruins. It was also found possible to make a solid light- 
giving substance by drawing a piece of string through 
a lump of tallow, and later this was modified by casting 
a solid fat around a wick, and thus the candle came into 
use. 

CANDLES 

The making of candles, by surrounding thin wicks of 
pith or flax with tallow or wax, dates from a very early 
period. In 1313 they are mentioned among the expendi- 
tures of the Earl of Lancaster. 1 Molded candles were 
introduced into England in the fifteenth century. 

1 Groves and Thorp, " Chemical Technology," Vol. II, p. 69. 



LIGHTING 57 

Candles are made from tallow, stearin, paraffin, wax, 
and spermaceti. Although tallow has been in use for a 
long time, there are serious objections to it because the 
fat melts at such a low temperature and drips. What 
was needed was a fat that had a higher melting point. 
This result was obtained by using a mixture of fatty 
acids produced from fats, instead of tallow. 

Fats and oils are derived from both the vegetable and 
animal kingdoms. They are really compounds of organic 
acids with bodies belonging to the group called alcohols ; 
that is, they are glyceryl salts of organic acids, mostly 
of the " fatty acid " group. The alcohol is usually 
glycerol or glycerin, C 3 H B (OH)3, and the compounds are 
called glycerides. The acids most commonly found in 
these glycerides are stearic, palmitic, and oleic. Solid 
fats contain more of the glyceryl tri-stearate or " stearin " 
and the glyceryl tri-palmitate called " palmitin." The 
liquid fats consist largely of the glyceryl tri-oleate or 
" olein." (See Soap, p. 128.) 

Tallow contains 75 % of stearin and olive oil only 25 %. 
One of the best products used in candle making is made by 
heating tallow until it melts, and then when it is partially 
cold putting it in bags in piles under a hydraulic press and 
squeezing out the liquid fat. This will be more fully 
discussed under Oleomargarine. 

There are several methods for separating the fatty acid 
from glycerin. This may be done by the use of steam, 
with lime, and with sulfuric acid. The commonest method 
is to heat under pressure with water, and a small per- 
centage of lime or zinc oxid, and afterward to distill with 
steam. This affords the two products, stearic acid, which 
earlier in the process is separated by gravitation, and 
glycerin, which is carried over with the steam; both of 



58 SANITARY AND APPLIED CHEMISTRY 

these are marketable. The stearic acid thus produced 
is quite crystalline, and indeed too much so to use alone 
in the manufacture of candles, and in actual practice 
it is mixed with a little paraffin to prevent crumbling. 

Two kinds of candles have been in use : dipped and 
molded. To make the former the wicks are dipped and 
allowed to cool and then repeatedly dipped again till the 
candle is large enough. A more modern method is to 
pour the melted fat into molds in which wicks have been 
previously suspended. Many attempts have been made 
to make a wick that will burn off at the end and not need 
snuffing. One of the best inventions in this line is the 
making of one thread of the twisted wick shorter than 
the rest so that the wick will be pulled over to one side 
and burned in the outer zone of the flame. 

Paraffin is one of the last of the products obtained by 
the distillation of petroleum. (See p. 60.) Illuminating 
oils and lubricating oils distill over earlier in the process. 
Paraffin is in reality a mixture of hydrocarbons, having a 
high boiling point, and as it is a mixture it cannot be repre- 
sented by a formula. 

SPECIAL ILLUMINATING MATERIALS 

There were some other interesting illuminating materials 
in use in the United States between the 40's and the 60's 
before kerosene was produced. One of these was cam- 
phene, which was simply refined turpentine. Another, 
which was intended to remedy some of the defects of 
camphene and prevent some of the smokiness of the 
flame, was called " burning fluid," and was a mixture of 
turpentine and alcohol. Various fixed oils, such as lard, 
whale, olive, colza, and poppy-seed, have been in use in 
lamps since the earliest times. Before the discovery 



LIGHTING 59 

and utilization of Petroleum an oil, known as " coal oil," 
was obtained by the distillation of certain coals, and a 
" shale oil " was made by the destructive distillation of 
bituminous shales. 

KEROSENE 

Oil was first found in Pennsylvania in 1859 by Colonel 
Drake. Kerosene is one of the products that comes off in 
the distillation of petroleum or rock oil. This oil is obtained 
by boring to a depth of 600 to 1800 feet, and is frequently 
associated with natural gas. The product from a large 
number of wells is carrried by pipe lines hundreds of miles, 
even through a mountainous country, to a refinery. There 
are more than 3000 miles of these pipe lines from the oil 
regions of Pennsylvania and adjoining states to lake or sea 
ports. In these pipes a barrel of oil moves forward every 
seven seconds, or at each stroke of the pump which keeps 
the oil moving. In the process of refining, the oil is heated 
in immense retorts, and the more volatile products are dis- 
tilled and condensed by passing through pipes surrounded 
by water. At a little higher temperature another product 
is given off, and another at a still higher, till at last a 
residue of paraffin remains, and this may be distilled off, 
leaving only a small amount of coke in the retort. Often 
the distillation is carried on in two stages, the " light 
oils " being first distilled, and then in another still the 
" heavy oils." 

DISTILLATES FROM PENNSYLVANIA PETROLEUM 

The commercial products obtained by the distillation 
of crude petroleum have various trade names, but the 
generally accepted classes of products are the following, 
beginning with the lightest : l — 

1 Sadtler, " Industrial Organic Chemistry," 4th ed., p. 29. 



60 SANITARY AND APPLIED CHEMISTRY 

1. Cymogene, which is gaseous at ordinary tempera- 
tures. It may be used in the manufacture of artificial ice. 

2. Rhigolene, which may be condensed to a liquid by 
the use of ice and salt. It is used as an anaesthetic. 

3. Petroleum ether, which boils from 40° to 70° C. It 
is used as a solvent for caoutchouc. 

4. Gasolene, which boils from 70° to 90° C. It is used 
as fuel and in gasolene engines, forming an explosive mix- 
ture with air. (It consists mostly of hexane (C 6 Hi 4 ).) 

5. Naphtha, which boils at 80° to 110° C. It is used 
in vapor lamps, and as a solvent for resins. 

6. Ligroine, which boils at from 80° to 120° C. It is 
used as a solvent. 

7. Benzine, 1 which boils at 120° to 150° C. It is used as 
a substitute for turpentine, and as a solvent. 

8. Kerosene or Burning Oil, which is graded by its color 
and " fire test." It has a flash test of 110° to 150° F. 

9. Lubricating oils, which have a gravity of from 32° 
to 38° Beaume. 

10. Paraffin, which is of different degrees of hardness, 
and like all the other products of variable composition. 
It is a solid, melting at from 51. °6 to 57. °3 C, and is used 
in candle making, in making water-proof papers, chewing 
gums, etc. Vaseline and petrolatum may be obtained 
from a mixture of some of the distillates. All these 
products are mixtures of hydrocarbons of the methane 
series. 

The crude kerosene is purified by treatment with sul- 
furic acid and alkali, and subsequently by bleaching in 
tanks with glass roofs. There is often a temptation to 
mix the lighter oils with the heavier, especially when the 

1 This is an entirely different product from' the " benzene" (CeHa) 
which is a coal tar distillate. 



LIGHTING 61 

former are cheaper and there is not so much use for them. 
These light oils, however, increase the danger of explo- 
sions when the oil is burned in a lamp. If a vapor is 
given off at the ordinary room temperature in the summer, 
or the lamp is heated so that a vapor may be given off 
from the oil, it may be mixed with air in such proportions 
that an explosion will result. The following grades of 
burning oil are on the market : — 

110° Fire test (Standard white). 
120° " " (Prime white). 
150° " " (Water white). 

In many states and countries laws have been passed 
fixing the " flash point," or the " fire test," of the oil, as it 
is called. By the " flash point " is understood the tem- 
perature at which a volatile vapor is given off that will 
produce an explosion. The " fire test " is the tempera- 
ture at which the oil will take fire and continue to burn. 
The laws of Ohio require a flash point not below 110° F. 
Those of New York require a higher point. In Kansas 
the requirement is the same as in Ohio, and the Foster 
cup is designated as the official tester. 

A simple flash-point apparatus may be made by the use 
of a small beaker filled about half full of kerosene, sup- 
ported in a larger beaker or vessel containing water. The 
oil may be heated at a rate not faster than two degrees in 
a minute. Over the beaker containing the kerosene is 
placed a metallic cover with a large opening. In this 
opening is placed a thermometer, with the bulb in the 
kerosene. A very small flame is applied at the opening 
above the kerosene from time to time, and a record is 
made of the temperature at which the slight explosion of 
the gas extinguishes the flame. This is the flash point. 



62 SANITARY AND APPLIED CHEMISTRY 

Experiment 25. Pour a small quantity of kerosene into 
a saucer, and touch it with a lighted match. The oil should not 
be ignited. 

Experiment 26. Pour about 2 cc. of gasoline into a sau- 
cer, and notice how readily it takes fire, and the smoky character 
of the flame. 

Experiment 27. Use a " Foster cup," or the flash-point 
apparatus described above, for testing the flash point of several 
samples of kerosene. 1 

ILLUMINATING GAS 

Aside from natural gas, which has already been discussed 
under fuels, the gas used for lighting is either coal gas, 
water gas, air gas, Pintsch gas, Blau gas, or acetylene gas. 

Illuminating gas, known as coal gas, was discovered by 
Clayton in 1664, and used for lighting a dwelling in Lon- 
don, by William Murdock, in 1792. It did not come into 
general use, however, for many years, for London was not 
lighted by gas till 1812, and Paris in 1815. 

Gas is made by the distillation of soft coal in fire-clay 
retorts, heated to a cherry red by a fire of coke, which is 
maintained beneath them. In addition to the gas, there 
are several by-products made, including gas carbon, 
which is found attached to the inside of the retorts, coke, 
ammoniacal water, and coal tar. The injurious gaseous 
constituents, including the sulfur compounds, are removed 
from the gas by cooling, washing, and passing it through 
lime purifiers, and then the gas is stored in large gas hold- 
ers, for distribution through the city mains. A ton of 
coal will yield from 8000 to 14,000 cu. ft. of gas. 

The gas carbon mentioned above is used in making elec- 
tric-light pencils and in batteries. The ammoniacal 
liquor is used for the manufacture of all the ammonia 
compounds of commerce. The coke is partly burned 

1 B. Redwood, " Petroleum and its Products," Vol. II. 



LIGHTING 63 

under the retorts, and the rest is sold as fuel, and finally 
the coal tar is distilled to make a variety of valuable 
organic substances, including many photographic de- 
velopers, the aniline dyes, carbolic acid, oil of winter- 
green, oil of " mirbane," salicylic acid, etc. 

WATER GAS 

Water gas is made by passing steam over incandescent 
coke or anthracite coal. This gives a mixture of the two 
gases, hydrogen and carbon monoxid, thus : — 

C + 2 H 2 = C0 2 + 2 H 2 . 
C + C0 2 = 2 CO. 

These gases, however, give no light, and so the gas is en- 
riched by injecting into the generator, by means of a jet 
of steam, some crude petroleum, which at the high tem- 
perature breaks up into volatile hydrocarbons, which 
furnish light when burned. On account of economy 
in manufacture, this gas is used instead of coal gas in 
many American cities. It is, however, much more 
poisonous, if breathed, than coal gas. 

AIR GAS 

Air gas was much used for lighting detached buildings 
before electric-lighting plants could be so cheaply in- 
stalled. In this process air is forced through vessels con- 
taining gasoline, and some of the vapor is thus carried with 
the air into the pipes. What is burned then is really 
gasoline vapor. In order to avoid danger from fire, the 
liquid gasoline is stored underground outside the building. 

PINTSCH GAS 

The method of making Pintsch gas, or oil gas, was in- 
vented in 1873, and it has found great favor as a com- 



64 SANITARY AND APPLIED CHEMISTRY 

pressed gas to use for lighting cars, steamboats, lighthouses, 
and isolated buildings. It is made from crude oil, by 
vaporizing it in cast-iron retorts. The oil is " cracked " 
in the upper chamber of the apparatus, and the vapor is 
passed into the lower chamber, which is heated nearly to 
1000° C. to " fix " the vapors and form permanent gases. 

BLAUGAS 

A process for making what is known as " Blaugas " 
was perfected by Herman Blau in 1901. One of the 
products produced by the fractional distillation of petro- 
leum is known as "gas oil." When this is heated to a 
high temperature in an apparatus free from air, it is de- 
composed, and oil gas is one of the products of the decom- 
position. This gas is liquefied at ordinary temperatures 
under a pressure of 20 atmospheres and the liquid is stored 
in strong steel bottles. These may be readily transported, 
and when the pressure is released the liquid again becomes 
a gas and can be stored in an expansion tank, from which 
it can be burned in the ordinary burners. It burns with 
a bright light, and a flame having a high temperature. 

ACETYLENE GAS 

Acetylene gas has come into use recently, since calcium 
carbid (CaC 2 ) has been cheaply made in the electric 
furnace by the use of powdered coke and lime. When 
calcium carbid is treated with water, acetylene gas is 
produced thus : — 

CaC 2 + 2 H 2 = Ca(OH) 2 + C 2 H 2 . 

This gas produces a very brilliant light, as there is much 
incandescent carbon in the flame. A burner which con- 



LIGHTING 



65 



sumes only half a foot of gas per hour is usually the most 
efficient, especially when the gas is burned under consid- 
erable pressure. It is not safe to compress the gas to 
more than two atmospheres, as an explosion is liable to 
occur. The gas finds considerable use in country houses, 
on yachts, automobiles, and bicycles. A ton of calcium 
carbid of 80 % purity will produce 10,000 cu. ft. of acety- 
lene gas. 1 Acetylene is freely soluble in acetone (CH 3 )2 CO. 
A solution of the gas in acetone under pressure is fur- 
nished for lighting automobiles. The gas is absorbed 
by asbestos contained in the steel cylinder. 

COMPOSITION OF ILLUMINATING GASES 

Illuminating gas gives the best results when burned at a 
water pressure of not over 1| in. If the pressure is too 
great, the gas " blows " and the light is decreased. The 
amount of gas burned in an ordinary burner is from 2 to 
8 cu. ft. per hour, dependent on the rating or size of the 
burner and the pressure of the gas. A comparison of the 
coal, water, oil, and natural gas may be made by inspec- 
tion of the following analyses : — 





Coal 


Water 2 
(Carbureted) 


PlNTSCH OR 

Oil 2 


Natural Gas " 


Carbon dioxid 


1.22 


3.00 


— 


.25 


Olefiant gas, etc. 


5.30 


16.60 


45.00 


.35 


Carbon monoxid 


7.50 


26.10 


— 


.41 


Marsh gas . . . 


38.11 


19.80 


38.80 


93.35 


Nitrogen . . . 


— 


2.40 


1.10 


3.41 


Oxygen . . . 


.22 


— 


— 


.39 


Hydrogen . . . 


47.65 


32.10 


— 


1.64 


Ethane .... 


— 


— 


14.60 


— 


Hydrogen sulfid . 


— 


— 


— 


.20 



1 Thorp, " Outlines of Industrial Chemistry," p. 293. 2 Ibid., p. 294. 
3 Min. Res. of U. S., 1893. Dept. Interior. Anal. Edw. Orton. 
F 



66 SANITARY AND APPLIED CHEMISTRY 

From these analyses it is evident that water gas, if 
breathed, would be the most liable to produce death, since 
it contains the most carbon monoxid. Natural gas con- 
tains less carbon monoxid than coal gas. 

Experiment 28. Test coal gas or any combustible gas 
for carbon dioxid, by passing it through limewater contained 
in a Woulfe bottle. For this purpose, put through a hole in 
one cork a tube bent at a right angle, with one limb extending 
to the bottom of the bottle, and through a hole in the other cork 
a tube of the same size, bent at a right angle, and passing just 
through the cork. Fill the bottle half full of limewater, allow 
the gas to bubble slowly through this, and light the gas that 
escapes. After a time, dependent on the amount of carbon 
dioxid in the gas, there will be a deposit of calcium carbonate 
in the bottle. 

Ca(OH) 2 + C0 2 = CaC0 3 + H 2 0. 

Experiment 29. To test the gas for hydrogen sulfid, allow 
a slow stream to pass through the empty Woulfe bottle arranged 
as above, in which is suspended a piece of filter paper which 
has been dipped in a solution of lead acetate. The paper will 
turn brown or black after a time on account of the formation 
of lead sulfid on the paper. 

Experiment 30. To test the pressure of the coal gas used, 
the apparatus mentioned in Experiment 28 may be used. If 
the bottle is small, a straight tube about eight inches (20 cm.) 
long may be put in to take the place of the longer bent tube. 
Fill the bottle about one third full of water. Connect the gas 
cock by means of a rubber tube to the shorter tube, and measure 
the height of the column of water raised by the pressure of the 
gas. 

Experiment 31. Learn to read a gas or water meter. The 
figures on the dial having the highest number are read first, 
and in case a pointer is very nearly upon any figure, notice 
by reference to the next lower dial whether it is above or below 
that figure, and read accordingly. 



LIGHTING 67 

Experiment 32. To make acetylene gas, put a small quan- 
tity of calcium carbid in a test tube. Place this in a rack or 
a test-tube holder, and carefully bring into the tube a few drops 
of water. The gas will be immediately given off and may be 
lighted. 

Experiment 33. To make an acetylene lamp use a heavy 
16 oz. flask or bottle provided with a cork having two holes. 
In one of these holes put a dropping funnel, with the tube extend- 
ing nearly to the bottom of the flask, in the other hole a tube 
bent at a right angle. Place about an ounce of calcium carbid 
in the flask, and allow water to drop on it, a very small quantity 
at a time, by the use of the dropping funnel. Pass the gas 
evolved through another flask or Woulfe bottle containing some 
lumps of calcium carbid; this will dry the evolved gas. In 
one tubulature of the drying bottle put a straight tube, to the 
top of which is fitted, by a short rubber tube, a special lava tip 
designed for burning acetylene gas which uses one half a foot 
of gas per hour. A brilliant light will be obtained. 

Experiment 34. In the incomplete combustion of illumi- 
nating gas small quantities of acetylene are formed. Study 
the phenomenon which takes place when a Bunsen burner 
" strikes back " and burns at the base. Notice especially the 
odor. 

LAMPS AND BURNERS 

A great variety of devices have been used to utilize 
oils and gas and get the greatest possible illuminating 
value from them. With a lamp, where kerosene or some 
oil is used as the combustible, the glass chimney came 
into use to increase the draft, and prevent smoking. If 
the substance burned is rich in carbon, as is the case 
with kerosene, this is particularly necessary. Another 
device to attain the same end that has been used in 
lighthouses is the use of a pump, run by clockwork, to keep 
the wick, especially of a large lamp, saturated with oil. A 



68 SANITARY AND APPLIED CHEMISTRY 

blower, concealed in the base of the lamp, has also been 
introduced, to avoid the use of a chimney. 

The invention of the Argand lamp in 1786, which was 
applied both to oil and gas, and in which the air enters 
the inside of the circular flame, was a distinct advance in 
illumination. The student lamp is of this type. The 
flat flame of the gas burner is obtained either in the " bat- 
wing " tip or the " fish-tail " burner. In the former, 
the gas comes out through a lava tip, which has a narrow 
slit in the top ; in the latter, the gas comes out through 
two opposite openings, usually in a metallic tip, and the 
resultant of these two currents of gas is a flat flame, at 
a right angle to the currents of gas. 

INCANDESCENT GAS LIGHTS 

On account of the fact that much of the gas in common 
use is of low candle power, and yet has great " fuel 
value," numerous attempts have been made to utilize 
this heat to produce light. Passing over many of the 
systems in use, the most practical at the present time is 
the Welsbach system. This was invented by C. Auer 
von Welsbach in 1885-1887. This lamp consists of a 
Bunsen burner over which is suspended a " mantle " of 
the oxids of such rare earths as cerium, thorium, yttrium, 
or zirconium. These oxids are obtained from the 
mineral monazite, which is mined extensively in North 
Carolina and Brazil. The best results are obtained by 
using a mixture of 99 % of thoria and 1 % of ceria. A 
cylinder of cotton is soaked in the nitrates of these metals, 
and one end is gathered into a ring by a thread of asbestos. 
After it has been dried, the cotton is burned off, and the 
oxids are worked into shape upon a form. Then, in 



LIGHTING 69 

order to preserve this fragile material, it is plunged into 
a bath of collodion, paraffin, or some similar substance 
which stiffens it. This latter material is burned off when 
the mantle is put in place over the Bunsen burner. The 
il life " of these mantles is from 500 to 1000 hr., and even 
if they have not become ruptured, after a time their 
candle power is very much lowered. In one experiment 
when burning 2.5 cu. ft. of gas per hour, at one inch pres- 
sure, at first 25.6 candle power was obtained, after 500 hr. 
only 18 candle power, and at the end of 1000 hr. 13.7 
candle power. 

This kind of burner, which is designed to utilize the heat 
of the gas, produces a high candle-power light, uses a mini- 
mum of gas, and is satisfactory with natural gas, water 
gas that has not been carbureted, or any gas that is a poor 
light producer. 

Experiment 35. To show the principle of light due to an 
incandescent solid, burn a piece of magnesium ribbon, or better 
still, heat a piece of calcium oxid in the flame of the oxyhydrogen 
burner. 

ELECTRIC LIGHTS 

In the modern method of lighting by electricity the 
common systems are the use of the arc light, in which 
pencils of gas carbon are heated by the electric current ; 
the incandescent, in which a filament of carbon contained 
in a bulb from which the air has been fully exhausted is 
heated by the passage of the current ; the tantalum lamp, 
in which the metal tantalum is used as the incandescent 
material ; the tungsten light ; the inclosed arc ; the mer- 
cury vapor lamp ; and the Nernst lamp. In these cases 
some highly heated solid gives out the light. 



70 SANITARY AND APPLIED CHEMISTRY 

LIGHTING SYSTEMS 

Most of the lights that have been mentioned are, at the 
best, wasteful, because we get heat and comparatively 
little light, when light and not heat is desired. Experi- 
ments have been made on the phenomenon of phospho- 
rescence, and on the light of the firefly, that show how 
much superior this is to any light devised by man. There 
seems to be no reason why man cannot hope to perfect 
some system of lighting that shall be as economical, and 
this is no doubt the light of the future. 

A recent author 1 quotes a table of light efficiencies 
which shows the relative amount of energy actually 
utilized from various sources as light : — 

Fireflies about 100 per cent 

Acetylene flame 4 to 5 per cent 

Welsbach burner 4 to 5 per cent 

Carbon filament, electric (4 watts per candle) 2 to 3 per cent 
Tungsten filaments, electric (1.25 watts per 

candle) 8 to 10 per cent 

Electric arcs 8 to 17 per cent 

Mercury vapor electric lamps (glass) . . . 5 to 6 per cent 

Nernst glower 5 per cent 

1 " Chemistry of Familiar Things," Sadtler, p. 38. 



CHAPTER V 
WATER 

As water is so essential to human life, it is evident that a 
study of its occurrence and liability to contamination 
may be undertaken with great profit. It is composed of 
two simple elements, hydrogen and oxygen, both invisible 
gases, and the purest water is, of course, that which is 
formed by the union of these gases. 

Water, when it is condensed in the clouds, is compara- 
tively pure, and as it falls through the atmosphere it dis- 
solves certain gases that are present in the air, and at the 
same time washes the air free from suspended organic and 
inorganic dust and bacteria. We are familiar with 
practically pure water in the form of distilled water, 
which is odorless and tasteless but to many is not agree- 
able as drinking water, because it does not contain the 
dissolved gases of the atmosphere nor the mineral salts 
to which they are accustomed. If it is aerated by shak- 
ing with air, and a very small quantity of salt is added, it 
becomes much more agreeable as a beverage. 

Natural waters may be divided into : rain water, which 
we collect in cisterns, spring water, brook, river, lake, well 
(both shallow and artesian), and, finally, sea water. 
There is another class of waters which are especially 
interesting from a medicinal standpoint, viz. mineral 
waters. 

71 



72 SANITARY AND APPLIED CHEMISTRY 

Cistern water may be collected practically pure, if it 
falls on a metallic or slate roof, and the first water of 
a rain is used to thoroughly wash the roof. A well- 
painted shingle roof may also be used for collecting the 
water, if sufficient care is exercised in washing the roof. 
The water of a cistern should be aerated by the use of some 
kind of a chain or bucket pump that will carry air into 
the water. This may be used as an auxiliary means of 
obtaining water from the cistern, even if an ordinary 
suction pump is used for domestic supply. 

Spring water, when it has flowed through sandstone or 
granite in an unpopulated region, is usually pure and free 
from mineral matter. In limestone countries, however, 
spring water is liable to become loaded with the mineral 
substances of the rocks and soil through which it perco- 
lates ; and on some of the alkali plains it becomes very 
strongly impregnated with mineral matter. There is a 
constant tendency for the mineral matter to concentrate 
in river water, and these waters, which contain the soluble 
materials of the soil, finally accumulate in the ocean. 
Dilution with nearly pure surface waters often prevents 
river water from increasing in mineral salts. The gases 
of the atmosphere, especially the carbon dioxid, assist 
very materially in the solution of some of the rocks. 
Spring water may also contain organic matter from 
peat swamps as well as dead algae and leaves which usually 
give it a brownish color. 

River water partakes of the character of the springs 
and brooks which feed it, and it is also liable to become 
contaminated from refuse and sewage which is poured 
into it from inhabited regions. As a large stream is so 
often used to carry off the " waste of civilization/' in the 
form of sewage, it is seldom, in a well-populated district, 



WATER 73 

that river water can be used with safety as a source 
of supply without some preliminary treatment by 
filtration. 

The water of the Great Lakes would be of the very best 
quality were it not for the fact that it is difficult to dispose 
of the sewage of the cities on the banks without con- 
taminating the water supply. This difficulty has been 
partially overcome, in many instances, by tunneling out 
several miles under the lake to an " intake " to get better 
water and by purifying the sewage. In the case of Chi- 
cago, by pumping the water containing the sewage 
through a drainage canal away from the lake into the 
Illinois River, the water supply is, to some extent, pro- 
tected. 

The water of wells will be pure or impure as the soil 
around them is pure or contaminated. Generally speak- 
ing, the water of bored and cased wells is purer than 
that of ordinary, shallow, dug wells, and the water of 
artesian wells, especially those which penetrate the earth 
to the depth of from 300 to 1000 ft., is usually better than 
that from shallow wells. As an ordinary well is but a 
hole in the ground, it naturally collects the surface im- 
purities in the vicinity, and in cities and large towns this 
water is liable to be very impure. It may contain min- 
eral salts, but the most dangerous impurities are of an 
organic nature. The character of these organic impurities 
is significant, as it is a key to the past history of the water 
and often reveals the fact that it has percolated through 
soil contaminated with sewage or the waste material 
from cesspools. As a district becomes more thickly popu- 
lated, there may come a time when the soil is saturated 
with filth, and then every rain will cause some of this to 
flow into the well. 



74 SANITARY AND APPLIED CHEMISTRY 

Although the water of wells is liable to be impure from 
cracks in the soil through which the foul water of drains 
or cesspools has entered, yet a commonly neglected 
source of infection is the surface drainage that may find 
its way into the well, because it is not carefully covered. 
When the water is pumped out and allowed to fall on 
dirty planks, where chickens and other animals resort, 
there is every opportunity for contamination. The same 
remark applies to cisterns, which sometimes receive not 
only the drainage of the soil, but of the dooryard where 
all the slops from the house are thrown. 

Artesian well water is usually free from dangerous or- 
ganic matter. The term " artesian/' a name derived 
from the province of Artois in France, where these wells 
were first used, applies, strictly speaking, to deep, flowing 
wells. In the United States there is a large area in north- 
ern Florida, and one in the vicinity of Charleston, South 
Carolina, also in Texas, in Kansas, and in California, 
where an abundance of water is supplied by artesian 
wells. In the city of Memphis, Tennessee, where some 
years ago there was an epidemic of yellow fever, great 
pains has been taken to obtain pure artesian water from 
deep wells. The analysis of this water, which was made 
some years ago by the author, showed it to be exception- 
ally pure, and the health of the city has been very much 
improved since its introduction. Some artesian wells 
have penetrated to such a depth or through such strata, 
that the water becomes impregnated with too much min- 
eral matter, so that it cannot be used for domestic pur- 
poses. This is the case, for instance, with a well bored 
at St. Louis to the depth of over 2000 ft. for supplying a 
brewery. The water contained so much salt that it 
could not be used. 



WATER 75 

MINERAL WATERS 

Mineral waters are those which contain an excess of 
some ordinary ingredients, or small quantities of some 
rare ingredients, and which on this account are used as 
remedial agents. There are besides these certain waters 
on the market, known as " table waters," which are 
simply very pure, and are recommended by physicians 
because they may be taken in large quantities and will 
produce good results on account of the quantity used. 

I. MINERAL SUBSTANCES IN WATER 

Some of the mineral substances found in natural waters 
and in mineral waters are the following : sodium, calcium, 
magnesium, iron, aluminum, lithium, and potassium, 
combined as silicates, sulfates, chlorids, carbonates, 
bicarbonates, and sometimes as borates and arsenates. 
Common mineral substances in waters may be tested 
for as follows : In making the tests for mineral substance 
in water, it is advisable to first test the water supply 
of the laboratory, and if it does not contain the substance 
tested for, then use a strong mineral water of known 
composition, like Apollinaris, Hunyadi-Janos, Manitou 
or Congress water. 

Experiment 36. Test for calcium in water that does not 
contain much iron by adding to it some ammonium chlorid, 
ammonium hydroxid, and ammonium oxalate. The forma- 
tion of a white precipitate of calcium oxalate, especially after 
boiling, indicates the presence of calcium. 

Experiment 37. Test for magnesium by first filtering off 
the calcium oxalate, if any is precipitated in the previous experi- 
ment, and adding to the filtrate, which should contain some 
ammonium chlorid and ammonium hydroxid, hydrogen sodium 



76 SANITARY AND APPLIED CHEMISTRY 

phosphate. The formation of a white crystalline precipitate 
of ammonium magnesium phosphate, especially upon shaking, 
indicates the presence of magnesium. 

Experiment 38. Test for iron as a ferric compound by 
adding a few drops of hydrochloric acid and some potassium 
ferrocyanid. The formation of a dark blue precipitate (Prus- 
sian blue) shows the presence of ferric salts. To test for ferrous 
salts, add to some of the water a few drops of hydrochloric 
acid and potassium ferricyanid. The formation of a blue pre- 
cipitate indicates the presence of ferrous compounds. 

Experiment 39. Another excellent test for ferric com- 
pounds is to add to a slightly acidified sample of the water 
a few drops of potassium sulfoeyanate. The production of 
a red color indicates iron. 

Experiment 40. Test for aluminum by adding to the water 
a few drops of ammonium chlorid and ammonium hydroxid 
in excess. The formation of a white flocculent precipitate, 
especially upon warming and allowing the solution to stand, 
indicates aluminum. In the presence of a considerable quan- 
tity of a ferric compound, the iron will be thrown down as a 
reddish precipitate, thus obscuring the aluminum hydroxid 
precipitate. 

Experiment 41. To test for lead, add to a sample of water, 

acidified with hydrochloric acid, a little hydrogen sulfid water. 
The formation of a black or brownish coloration will indicate 
lead. 

Experiment 42. In order to show how readily water, espe- 
cially when pure, attacks lead, scrape a piece of sheet lead 
till it is bright and clean. Place it in a beaker of distilled 
water, and allow to stand for an hour or more. Remove the 
lead from the water and test the water for lead in solution by 
the use of hydrogen sulfid water. 

Experiment 43. Test for sulfates by acidifying a sample 
of the water with hydrochloric acid, and adding a few drops 



WATER 77 

of barium chlorid. The formation of a dense white precipi- 
tate of barium sulfate, especially after boiling, indicates the 
presence of sulfates. 

Experiment 44. To test for chlorids, add a few drops of 
nitric acid to the sample, and then silver nitrate. The forma- 
tion of a white precipitate of silver chlorid indicates chlorids. 

Experiment 45. To test for the total amount of mineral 
matter in the water, evaporate from 100 cc. to 200 cc. in a small 
weighed porcelain or platinum dish on a water bath. Dry 
the residue at 120° C, and weigh. Calculate the weight in 
terms of grams per liter. (The dish can be weighed on the 
ordinary horn-pan balance.) 

Experiment 46. To test for carbonates, add a few drops 
of hydrochloric acid to the residue obtained in the previous 
experiment. If carbonates are present, there will be an efferves- 
cence on account of the escape of carbon dioxid gas. This 
solution may then be tested for potassium and sodium by dipping 
into it a platinum wire, which is heated in the Bunsen burner, 
and the flame can be examined with the spectroscope. 

Experiment 47. To test for sulfur or hydrogen sulfid in 
a water like that from sulfur springs, plunge a silver coin into 
the water, and in the presence of soluble sulfids it will be quickly 
blackened on account of the formation of silver sulfid, Ag 2 S. 

HARD WATERS 

Some waters contain large quantities of calcium, mag- 
nesium, iron, and aluminum. Those which contain these 
metals associated with the carbonate radical making 
calcium acid carbonate, magnesium acid carbonate, etc., 
are called temporarily hard waters, and those which con- 
tain calcium, magnesium, iron, or aluminum sulfates 
or chlorids, are called permanently hard waters. This 
distinction is made because the carbonate waters can be 



78 SANITARY AND APPLIED CHEMISTRY 

readily softened by adding to them limewater in sufficient 
quantity, while it is much more difficult to soften the 
permanently hard waters. Another reason for this 
distinction is that a considerable quantity of the mineral 
matter is precipitated by boiling, in accordance with 
the equation : — 

CaH 2 (C0 3 ) 2 + heat = CaCQ 3 + C0 2 + H 2 0. 

The difference between the hard and soft water may be 
readily shown by the action of a soap solution upon the 
two varieties. 

Hard waters produce serious inconvenience when used 
in steam boilers, depositing a scale of greater or less thick- 
ness, which causes great loss of fuel by interfering with 
the transmission of heat to the water, and is liable, if it 
becomes thick enough, to allow the iron to become over- 
heated, and greatly increase the tendency to explosion. 
The same kind of a scale is often found in a teakettle 
when hard water is used. There is an immense advantage 
in substituting soft water for hard when the item of soap 
is considered. It is estimated that in Glasgow, where 
the soft water of Loch Katrine was substituted for hard 
water, there was a saving in soap to the inhabitants of 
the city of nearly $200,000 annually. 

For a long time it was believed that the disease " goiter " 
was due to the use of certain kinds of hard water, and the 
prevalence of this disease in some parts of Switzerland, 
France, Austria, India, and Derbyshire, England, was 
cited as proof that this was the case. In some cases, as 
in the city of Vienna, 1 there does seem to be a relation 
between the water used and the prevalence of the disease. 
Some have thought that a microorganism in the water 

1 " Preventive Medicine and Hygiene," Rosenau, p. 807. 



WATER 79 

caused the disease, but this theory also remains to be 
proved. Lobenhoffer believes that the cause of goiter is 
a purely chemical substratum substance, which enters 
the water as a toxin but is surely destroyed at 70° C. 

Experiment 48. Prepare a sample of very hard water by 
adding some calcium chlorid to a sample of ordinary water, 
and pour this into a tall cylinder. Add to this some soap solu- 
tion, 1 shake thoroughly, and notice how many cubic centi- 
meters of the soap solution must be used before a permanent 
lather is produced in the water. Compare this with a similar 
experiment made with soft or distilled water. Notice also the 
abundant precipitate of " lime soap " in the hard water. 

II. ORGANIC MATTER IN WATER 

The mineral constituents of water : those which give 
character to the so-called mineral waters, which make 
water hard, which give saltness to brine, and the peculiar 
characteristics to the " alkali " waters of the plains, 
have been previously discussed. There are, however, 
other substances in waters which it may not be possible 
to detect there either by the sense of taste, smell, or sight, 
and yet these substances, which constitute the " organic 
matter/ ' are from a sanitary standpoint of the greatest 
importance. 

As has been stated, the mineral matter comes from the 
decomposition of the rocks and of the soil through which 
the water percolates. In a similar way, the organic 
material comes from the soil through which the water 
passes, or over which it runs. It is difficult to tell the 
source of the organic matter from a simple analysis of 

1 To make a soap solution Mason ("Water Supply," p. 360) recom- 
mends to use 10 g. of Castile soap, scraped into fine shavings, and 
dissolved in a liter of alcohol diluted with one third water. Filter, if 
not clear, and keep in a tightly stoppered bottle. 



80 SANITARY AND APPLIED CHEMISTRY 

the water. It may come from peat swamps in which 
decomposing vegetable matter has remained for a long 
time in contact with the water; it may come from the 
decayed leaves or wood ; or, what is much worse, it may 
be from decomposed animal matter, which finds its way 
into a stream or well from some cesspool or barnyard 
or foul kitchen drain. 

The chemist in making a sanitary analysis of a water 
determines its color, odor, and turbidity, as well as the 
residue left on evaporation, loss on ignition of this residue, 
free ammonia, albuminoid ammonia, nitrogen present 
in nitrites, nitrogen present in nitrates, chlorin, oxygen 
consuming power, and hardness. He also studies the 
number and character of the bacteria which are present. 
From a consideration of all this data; from a knowledge 
of the locality from which the water comes ; from com- 
parisons with other waters from the same locality, all 
taken together he is able to form an opinion as to whether 
the water is safe for domestic use. 

The ammonia is not in itself injurious, but is an index 
of nitrogenous matter, which is liable to be dangerous. 
Whenever there is matter of this kind, numerous bacteria 
find the conditions suited to their growth. 

Free ammonia is usually considered to be indicative 
of recent contamination, especially of animal origin, while 
albuminoid ammonia indicates more especially nitrogenous 
matter that has not undergone sufficient decomposition 
for the formation of ammonia compounds. If the water 
changes in its ammonia content from day to day, this 
also shows that it is in a dangerous condition. As to the 
amount of these substances which may be allowed in a 
good water, it is practically impossible to set a standard, 
as local conditions are so variable. What would be a 



WATER 81 

fair standard for water from one locality, would not 
apply at all to water from a different locality. Professor 
Mason reports an excellent mountain stream containing 
.055 part of free ammonia and .230 of albuminoid am- 
monia per million. Professor Mallet reports the average 
of a number of city supplies considered good as containing 
.152 part of albuminoid ammonia, and Professor Leeds 
would limit the amount to free ammonia .01 to .12 per 
million and albuminoid ammonia .10 to .28 per million. 
It is interesting to note that iron waters always contain 
much free ammonia. 

Free ammonia is determined in a water by distilling a 
half liter and testing the several portions of 50 cc. of the 
distillate with Nessler solution. The brown color pro- 
duced is compared with that obtained in solutions of 
ammonia of known composition. When the free ammonia 
has been distilled off, some alkaline permanganate solu- 
tion is added, and the ammonia thus set free on distilla- 
tion is determined as before. This is the albuminoid 
ammonia. 

The nitrites in water are indicative of a changing con- 
dition of oxidation, which is completed when the nitroge- 
nous bodies are changed to nitrates by bacterial action 
or by oxidation of nitrites. The determination of ni- 
trates is considered of value in supplying some data as 
to the previous history of water. If the nitrates are 
abundant, this indicates that at some earlier stage in the 
history of the water it may have been contaminated with 
sewage, and although there may be no free ammonia 
present, we have no proof that the pathogenic germs, 
that once existed in the water, are destroyed by the 
oxidation which the ammonia has undergone. 

In regard to the nitrates, it is evident that there must 



82 SANITARY AND APPLIED CHEMISTRY 

be some of these in natural waters, for both nitrites and 
nitrates are washed out of the air and carried into the 
soil, and we depend upon the nitrates as well as other 
nitrogenous compounds in the soil to assist in the growth 
of plants. The determination of nitrates is regarded by 
Mallet as of great importance, and he places the figures 
for the amount as averaging 0.42, the extreme limit being 
1.04 parts per million. He notices that waters known 
to be polluted contain sometimes from 7.239 to 28.403 
parts of nitrogen as nitrates per million. The average 
for American * rivers is given as from 1.11 to 3.89 
parts per million, and the author has found in city- 
wells from 14.5 to 150 parts per million of nitrogen as 
nitrates. 

The Rivers Pollution Commission (Eng.) gives the 
following averages from 589 unpolluted waters for nitro- 
gen as nitrites and nitrates. 

Parts per Million 

Rain water 03 

Upland surface 09 

Deep well 4.95 

Spring 3.83 

In some localities the determination of chlorin may be 
of value, especially where the normal chlorin content of 
the ground water is known. The soil of several of the 
New England states has been thoroughly studied, the 
normal amount of chlorin for each locality has been pretty 
accurately determined, and a map has been prepared 
showing where equal amounts of chlorin are found. An 
increase in chlorin would show probable pollution with 
sewage. In many places, however, there is so much 
salt in the soil that the determination of chlorin is of no 
value. 



WATER 83 

Experiment 49. To make Nessler's solution, dissolve 8 g. 
of mercuric chlorid, HgCl 2 , in a quarter of a liter of pure water. 
Dissolve 17 g. of potassium iodid, KI, in 100 cc. of pure water. 
Pour the first solution into the second until a slight permanent 
precipitate, which does not disappear on shaking, is produced. 
Add 80 g. of solid potassium hydroxid, KOH, dilute to one half 
a liter, cool, and add drop by drop some of the mercuric chlorid 
solution till there is a slight permanent precipitate. Allow to 
settle for some time, and pour off the clear yellowish solution 
for use. Old " Nessler Solution " is better than one which is 
recently made. 

Experiment 50. Test a sample of the distilled water used 
in the laboratory for ammonia by placing some of it in a long 
test tube, or a so-called Nessler tube, standing on a piece of 
white paper, and adding to it 2 cc. of Nessler solution. Notice 
the brown tint of the solution. 

Experiment 51. Distill about 500 cc. of well or river water 
slowly from a liter retort, condense the steam by a Liebig's 
condenser or in a flask floating in a pan of water, and test about 
50 cc. in a long tube by adding 2 cc. of Nessler solution, and 
allowing the mixture to stand a few minutes. Unless the water 
is very pure, there will be a distinct brown coloration. 

Experiment 52. To test for nitrates in water, add to about 
10 cc. in a test tube an equal quantity of concentrated sul- 
furic acid and cool the solution. Then add to this cautiously, 
without mixing, a strong solution of ferrous sulfate. The 
formation of a brown ring where the two liquids come together 
j indicates the presence of nitrates. This test is delicate only 
iito about ten parts of nitric acid in a million parts of water. 
A very small crystal of saltpeter, potassium nitrate, may be 
I used in the water to show the test. 

Experiment 53. To test for organic matter when present in 
large quantity, as in a foul cistern water, add to a sample of water, 
contained in a tall stoppered cylinder, a little dilute sulfuric 
acid and a few cubic centimeters of a 1 % solution of potassium 
permanganate. The purple color of this solution is "discharged " 



84 



SANITARY AND APPLIED CHEMISTRY 



by shaking with water containing organic matter, so the amount 
of organic matter may be estimated relatively by noticing how 
much permanganate must be used to produce a permanent 
purple color in the water. (This same reagent may be used 
practically on a large scale to remove the foul odor of cistern 
water. Potassium permanganate should be added to the 
water until, on mixing, there is a slight pink tint to the water.) 

Analysis of City Water Supply 1 
(parts per million) 



^ 



o 3 

p i 

ffl s 



o 






>-7 m 



^p 



O 0D 



Springfield, Mass., Aver. 1893 . 
Boston, " " 1894 . 
Burlington, Vt. (Lake Cham- 
plain) 

Poughkeepsie, N.Y. (Hudson R.) 
Rock Island, 111. (Miss. R.) . . 
New Orleans, La. (Miss. R.) 
Charleston, S.C. (artesian well) 
Brooklyn, N.Y. (ground water) 
Cincinnati, Ohio (Ohio R.) . . 
Philadelphia (Schuylkill R., 

average of 22) 

New York, weekly average for 
1894 



.009 
.006 

.035 
.050 
.025 
.040 
.300 
.001 
.003 

.010 

.012 



.204 
.319 

.140 
.125 
.260 
.325 
.040 
.085 
.108 

.100 

.082 



1.50 
4.10 

0.70 
4.50 
1.00 
14.50 
130.00 
13.50 
14.00 



2.47 



.001 
.001 


trace 




.368 





.026 
.106 

trace 
trace 
trace 

.080 

16.000 

.260 

.460 

.258 



5.132 
6.295 

1.525 

2.287 
6.000 
5.724 
2.043 



37.6 
46.4 

70.0 

85.0 

140.0 

340.0 

1170.0 

64.0 

140.0 

133.4 

81.6 



DRINKING WATER AND DISEASE 

It should be noticed in the first place that while peaty 
waters contain quite large quantities of organic matter, 
this is not considered as injurious as other kinds of organic 
material. The best authorities seem to agree, however, 
that its presence does tend to induce diarrhoea and malaria. 

1 "Water Supplies," Mason, 3d edition, p. 415. 



WATER 85 

According to recent investigations the prevalence of 
malaria in certain localities is found to be due to the low 
land and numerous puddles where the mosquitoes that 
transmit the infection have a chance to breed. 1 It should 
also be said that though a water of this class may be harm- 
less at some stages of its history, at other stages it may be 
injurious on account of the decomposition that has taken 
place. Another water containing a large quantity of 
organic matter is the so-called sawdust water, which is 
obtained from wells sunk in " made " land in the vicinity 
of streams where sawmills have been located. This is, 
without doubt, injurious. 

In regard to hard waters, the opinion seems to be pre- 
dominant that the mortality is practically uninfluenced 
by hard or soft water. 

In many localities, waters that are extremely turbid 
are used for domestic purposes, and it is evident that 
they are used without apparent serious injury, when we 
consider the population and the death rate in such cities 
as Cincinnati, Louisville, and St. Louis. The death rate 
was very much lowered after filtration of the water supply. 
This should be said, however, that while these waters 
are used with impunity by those who are accustomed 
to their use, strangers for a time are frequently seriously 
affected by the use of such waters. 

A much more serious class of impurities is those which 
come from the introduction of sewage into the waters, and 
although they may be perfectly clear, transparent, and 
of good taste, such waters are often extremely dangerous. 
The question arises, Shall the water once polluted by 
sewage be used for human consumption? If there is 
danger in such use, What is its extent, and can such 

1 "Practical Hygiene," Harrington, p. 649. 



86 SANITARY AND APPLIED CHEMISTRY 

danger be avoided? A few examples of pollution of 
water by sewage will be of interest. 

In 1887 * the city of Messina, Sicily, was visited by an 
epidemic of cholera. From September 10 to October 25 
there were 5000 cases and 2200 deaths. The government 
investigated this epidemic, and it was found that though 
the water which was supplied to the city left the gathering 
grounds in the mountain of good quality, part of it was 
diverted on its way to the city, and used by the washer- 
women of the vicinity for washing clothes, and was after- 
ward conducted back into the open canal which supplied 
the city. As soon as the authorities sent tank ships to 
the mainland and obtained pure water for use in the city, 
the plague ceased as if by magic. 

In 1890 there were two violent epidemics of typhoid 
fever in the valley of the Tees in England. The country 
which supplied the water was not thickly populated, and 
the water was apparently good. It was found, however, 
that many of the towns discharged their sewage into the 
stream, and in dry weather the stream receded, leaving 
its banks dry and exposed. Here the filth accumulated, 
and in times of high water this was swept into the stream, 
and was afterward pumped into the reservoirs and used 
as the source of water supply. It was noticed that an 
" increase of rainfall was followed by an increase in the 
number of cases of typhoid fever among those persons 
using the Tees water, after an interval corresponding 
to the incubation period of the disease, while no appre- 
ciable result was noticed among those people of the dis- 
trict using other sources of supply. 7 ' 2 

One of the most interesting cases is that of the city of 
Plymouth, Pennsylvania, containing 8000 population. 

1 Mason, " Water Supply," p. 24. 2 Ibid., p. 27. 



WATER 87 

In a few weeks there were more than 1000 cases of typhoid 
fever and 100 deaths. The water supply was obtained 
from a mountain brook. There were but few houses on 
the banks of this brook, and it would seem that the water 
was well protected from sources of contamination. On 
investigation, it was learned that while the stream was 
frozen a man had been sick with typhoid fever, and had 
been cared for in a house near the source of this moun- 
tain brook. The discharges were thrown upon the snow, 
and when this melted in the spring the filth was swept 
into the stream. The inhabitants of the village of Plym- 
outh were obliged to use this water for a time as their 
source of supply, instead of the Susquehanna River, so 
the Bacillus typhosus was pumped to all parts of the city. 
It was noticed that whole groups of families using well 
water escaped, while those using the city water were 
afflicted with typhoid fever. It was estimated that aside 
from the deaths that occurred, the money losses to 
this community in wages and care of the sick was over 
$100,000. 

AH are more or less familiar with the conditions at the 
time of the terrible outbreak of cholera in Hamburg, Ger- 
many, in 1892. The city had a population of 640,000. 
The epidemic lasted for about three months, and the 
total number of cholera cases was 17,000, with 50 % mor- 
tality. Hamburg is close to the city of Altona ; in fact, 
these two together with Wandsbeck are practically one 
city, but they obtain their water from different sources. 
Hamburg pumps water from the Elbe River, the intake 
being just south of the city. Altona pumps its water 
from the Elbe at a point about 8 miles below that at which 
the river receives the sewage of the three cities ; but in 
the case of Altona the water which has received the sewage 



88 SANITARY AND APPLIED CHEMISTRY 

from a population of 800,000 people was filtered with 
exceeding care before being delivered to the people. It 
was interesting to notice in this case that in some sections 
of the city, people supplied with the Hamburg water were 
afflicted with cholera, while those on the other side of the 
same street using the Altona water were not afflicted, and 
this immunity from cholera of those using the Altona 
water was noticeable all over the city. 

The analysis of the Hamburg supply showed in parts 
per million : — 

Free ammonia 1.065 

Albuminoid ammonia .293 

Nitrates 26.430 

Chlorin 472.000 

The case of the outbreak of typhoid fever at Lausen, 
Switzerland, is also very instructive. The source of the 
epidemic was traced to an isolated farmhouse on the oppo- 
site side of the mountain, where three cases of the fever 
occurred. The brook which ran past the house was after- 
wards used for irrigating some meadows, and then filtered 
through the intervening mountain to a spring in Lausen, 
from which all the people, except those in six houses, 
obtained their water supply. In the six houses no cases 
of fever occurred, but scarcely any in the other houses 
escaped. By dissolving a large amount of salt in the 
water on the other side of the mountain, and observing 
the great increase of chlorin in the spring water, the 
source of the infection was traced, and to show how thor- 
oughly the water was filtered, a quantity of flour was 
mixed with the brook water, and not a trace was found 
in the spring water at the village. This showed that 
filtration through the rocks and soil of the mountain did 
not remove the dangerous infection. 



WATER 89 

" Under ordinary conditions no multiplication of typhoid 
bacillus takes place in water even when a considerable 
amount of organic matter is present, but on the contrary a 
steady decline in numbers goes on. The history of 
typhoid epidemics tends to show that sewage pollution 
is to be feared chiefly when the sewage is fresh, and that 
the danger of infection diminishes with the lapse of time. 
In soil the duration of life of the typhoid bacillus is much 
longer than in water.' ' l 

In conclusion, then, any source of supply may be con- 
taminated, and there is danger in the use of well waters, 
especially in crowded districts. Numerous diseases are 
distributed by impure waters, and, in any case of an 
epidemic of those diseases that are caused by specific 
bacteria, the water supply should be very carefully exam- 
ined, and it is always advisable at such times to boil 
the water before using. 2 

1 " Sewage Disposal," Fuller, p. 122. 

2 Consult for further details, " A Text Book of Hygiene," Rohe and 
Robin. 



CHAPTER VI 

PURIFICATION OF WATER SUPPLIES 

NATURAL PURIFICATION 

Water is naturally purified by sedimentation, dilution, 
oxidation, filtration, vegetable growth, and bacterial action. 
The extent to which each of these agencies improves the 
water depends on a variety of circumstances. With the 
deposit of mud and silt there is often carried down a large 
amount of organic matter; indeed, the presence of a 
certain amount of suspended matter in some of the West- 
ern rivers seems to assist in the removal of organic im- 
purities. Sedimentation as ordinarily practiced, how- 
ever, will not purify an unsafe water. 

Dilution of a small stream carrying sewage by a large 
stream of purer water seems to make it of better quality, 
but really the organic matter is simply distributed through 
a larger volume of water, and not necessarily destroyed. 

Oxidation, by a rapid fall, or by exposure to the air in 
running over riffles, as in a shallow stream, has been 
depended upon formerly for a large amount of purification. 
There is a difference of opinion, however, as to the extent 
to which oxidation will destroy pathogenic germs. W. C. 
Young 1 states, as the result of his experiments, that the 
removal of dissolved organic matter from river water 
by natural means is extremely slow. The principal 

1 Jour, Soc. Chem. Ind., Vol. 13, p. 318. 
90 



PURIFICATION OF WATER SUPPLIES 91 

agent in this purification is the growth of vegetable 
organisms, and atmospheric oxidation has little effect. 
It has been recently shown that standing water, not run- 
ning water, effects self-purification most rapidly. 

ARTIFICIAL PURIFICATION 

History 

It is possible to purify water on a large scale under 
the control of a public water supply company much more 
economically and thoroughly than can be done by house- 
hold filtration. Furthermore, the tests for purity and 
the control of the supply as a whole can be handled at 
comparatively small expense, for a large urban population. 

On this account, following the methods inaugurated 
in Europe many years ago, the city of St. Louis attempted 
to improve its water supply as early as 1866, and in 1887 
and the years following the Massachusetts State Board 
of Health carried on experiments for the purification of 
water and sewage in connection with the water supply 
of Lawrence, Massachusetts. It is notable that the 
filter here introduced was found to be very efficient and 
the use of the filtered water reduced the death rate from 
typhoid fever 79% in five years. Experiments made 
in Louisville, Kentucky, upon the Ohio River water 
resulted in the installation of a very complete filtration 
system. Other cities, as Washington, D.C. ; New 
Orleans ; Springfield, Massachusetts ; Cincinnati ; St. 
Louis, and Baltimore, have put in improved filter plants 
and furnish at the present time water of a high degree of 
purity from adjacent rivers. Either rapid sand or slow 
sand filters are now in use in all the large cities of the 
country where river water is utilized as a source of supply. 



92 SANITARY AND APPLIED CHEMISTRY 

METHODS OF PURIFICATION 

Water, to be safe and harmless for domestic use, must 
be practically free from all bacteria in order that the 
pathogenic bacteria may be completely removed. It 
should also be free from suspended matter, from odors 
and tastes that are disagreeable, from iron, and from 
color. If to be used for industrial purposes, water should 
be practically soft and of low mineral content. 

The practical methods for purifying water are : — 

(a) Coagulation and Sedimentation. 
(6) Slow Sand Filtration. 

(c) Rapid Sand or Mechanical Filtration. 1 

(d) Combinations of (a +b J or (a + c) or (a + c + b). 

(a) Coagulation and Sedimentation. 

Although sedimentation alone will greatly improve a 
water, yet we do not at the present time depend on 
this process. Coagulation with sedimentation has 
been used on the muddy streams of the Middle West 
with considerable success. The coagulants to be added 
to the water as it is drawn into the settling basins are 
ferrous sulfate, lime, and alum. Large settling basins, 
which will hold a supply for two or three days, are re- 
quired. The coagulum carries down a large per cent of 
the bacteria contained in the water. 

(6) Slow Sand Filtration. 

This process, which is widely used on the Continent, 
is also used in treating the supplies of some of the 
larger cities in the United States. The water is first 
allowed to settle, sometimes with the use of a coagulant, 
and in this way a large percentage of the suspended ma- 

1 " Water Purification Plants and Their Operation," Stein, p. 21. 



PURIFICATION OF WATER SUPPLIES 93 

terial is removed. The settled water is then allowed to 
flow uniformly over a sand filter, which is made of clean 
quartz sand, three to four feet in depth, overlying a bed 
of gravel, graded to increase in coarseness towards the 
bottom. Open- jointed tile pipes serve to withdraw the 
water under the gravel. The best results are attained 
by allowing the water to flow through the filter at the 
rate of about 3,000,000 gallons per acre per day. After 
the filter is in operation, it will be found that a slimy 
gelatinous film forms on the surface and between the 
sand grains. This jelly is largely of bacterial origin, 
and helps very materially in holding back the silt and 
bacteria in the water. 

When the filter becomes clogged, it is shut down and 
drained, and the surface is removed to the depth of one- 
half inch or more, with broad, flat shovels. The removed 
sand is afterwards washed in such a way as to take out 
all the slime and silt, and is again used in the filter. The 
efficiency of this variety of filter increases for some time 
after the filter is first installed, as the mat or slime of 
bacteria and organic matter increases in thickness. It 
is evident that the area of the filter beds must be large 
enough so that some beds can be cleaned while others 
are in use. As an illustration of the efficiency of this 
system of purification, it is noted that in the Altona case 
the average number of germs in the unfiltered water was 
28,667 per cc. and in the filtered water only 90, so 99.67 % 
were removed. The removal of the bacteria is not due 
simply to the straining, but the conditions within the 
filter are unfavorable to the life of the bacteria. Since 
the food material for bacterial growth is gradually taken 
away, the water actually improves in quality as it flows 
through the service pipes to the consumer. 



94 SANITARY AND APPLIED CHEMISTRY 

(c) Rapid Sand or Mechanical Filtration. 

This is also best performed with the use of a coagulant. 
The water is purified so far as possible by sedimentation, 
as in the previous process, then mixed with the requisite 
quantity of the coagulant (alum, lime, or an iron salt), 
and, when the water is to be more completely softened, a 
solution of soda-ash is added. If the water is "temporarily 
hard," alum may be used in the treatment, as the calcium 
bicarbonate present will cause the precipitation of alu- 
minum hydroxid. 

The water is forced through a bed of sand contained 
in a tank, and when this sand becomes clogged, the water 
is turned off and a reverse current coming from below 
washes the sand for about fifteen minutes. In this pro- 
cess the silt and precipitate of iron or aluminum hydrate, 
being lighter, is carried over the partitions of the tank 
into the waste, while the sand continually settles to the 
bottom of the basin. After the sand is thoroughly 
cleansed, the unpurified water is again turned on. In 
this method of treatment the " bacterial jelly " of the 
slow sand filtration process is replaced by an artificial 
inorganic jelly or gelatinous precipitate which effectively 
entangles the bacteria and reduces the amount of organic 
matter in the water. 

WATER-SOFTENING 

The advantages of using a soft water have already 
been referred to (p. 78). It is possible to soften a water 
at the same time that it is filtered, and with a few modi- 
fications the mechanical filter plant can be used for this 
purpose. Larger sedimentation basins and facilities for 
mixing lime and soda-ash with the water must be pro- 
vided. 



PURIFICATION OF WATER SUPPLIES 95 

In the Clark process of softening, the bicarbonate of 
calcium, magnesium, and iron, the substances which 
cause " temporary hardness/' are precipitated by the 
addition of an excess of lime. This is in accordance with 
the following equation : — 

CaH 2 (C0 3 ) 2 + Ca(OH) 2 = 2 CaC0 3 + 2 H 2 0. 
The sulfates, chlorids, and nitrates of calcium and mag- 
nesium, which cause " permanent hardness " (p. 77), 
are precipitated by the addition of " soda-ash " (crude 
sodium carbonate) as follows : — 

CaS0 4 ] [ Na 2 S0 4 

CaCl 2 [ + Na 2 Co 3 = \ 2 NaCl + CaC0 3 

Ca(N0 3 ) 2 J [ 2 NaN0 3 

and in the case of magnesium salts : — 

MgS0 4 1 fNa 2 S0 4 ) 

MgCl 2 + Ca(OH) 2 = 2 NaCl + Mg(OH) 2 . 

Mg(N0 3 ) 2 J [ 2 NaN0 3 J 

It is not necessary or advisable to remove the mineral 
matters in a water by precipitation and filtration below 
50-75 parts per million. 

DISINFECTION 

In some circumstances, as when it is not possible to 
completely purify the water by filtration, or when there 
is an unexpected demand upon the source of supply, 
or in case of accident to the purification plant, it is of 
advantage to have some means of protecting the users 
of the water from infection by the disease germs that 
may be present in the water. At one time copper sulfate 
and also potassium permanganate were recommended. 
Later ozone was tried, and found to be efficient in destroy- 



96 SANITARY AND APPLIED CHEMISTRY 

ing bacteria, but its use was expensive. Ultra-violet light 
has also been recently used with success. 

In 1908 hypochlorite of lime (bleaching powder) was 
tried and found to be a very satisfactory disinfectant 
at a low cost. At the present time chlorin, as bleach- 
ing powder or as liquid chlorin, has come to be very 
extensively used in city water supplies, because in 
its use there is such a gain in hygienic safety. Great 
care and skill are, however, required, lest disagreeable 
tastes and odors be produced by the use of an excess. 

HOUSEHOLD PURIFICATION OF WATER 

For those living in isolated houses, or where there is 
no public source of supply, it is often necessary to filter 
or otherwise purify the water before it is safe for domestic 
use. For filtration some device of porous stone or tile, 
or sand may be used. The filter should be of such con- 
struction that, if of stone, it can be readily cleaned with 
hot water and a stiff brush, or if of sand or similar porous 
material, by thoroughly washing. Filters made of un- 
glazed porcelain, of the Pasteur-Chamberland type, 
or of diatomaceous earth like the Bekefeld filters, 1 
have been shown to be extremely efficient, as practically 
all the bacteria in the water are removed by their use. 
In another style, plates of artificial stone are used as the 
filtering material. In all these filters the water, even if 
under pressure, percolates quite slowly through the ma- 
terial. Filters which are attached to a faucet and deliver 
the water rapidly are of little value to remove bacterial 
infection. 

Boiling the water can always be depended upon to make 
a water safe, and this should always be resorted to in 

1 "Preventive Medicine and Hygiene," Rosenau, p. 793. 



PURIFICATION OF WATER SUPPLIES 97 

doubtful cases. It is only necessary to heat to boiling, 
or at most to boil for five minutes to destroy all pathogenic 
bacteria in the water. Boiling for twenty to thirty min- 
utes may be necessary, should it be desired to fully ster- 
ilize the supply. 

Bleaching powder and also ozone and ultra-violet light 
may also be used to purify a domestic supply, but these 
methods are not as convenient as those previously men- 
tioned. 

The good effect of freezing has been very much over- 
estimated. Clear, transparent ice, from the surface of an 
open body of water, when melted, yields about 10 % as 
many bacteria as were present in the original water. If 
a pond freezes solid to the bottom, all the impurities that 
were in the water will be in the ice. 

Experiment 54. The action of a coagulant may be illus- 
trated by putting a few grams of alum into a sample of water, 
and adding to it enough of a tincture of cochineal to give it a 
strong red color. Add to this ammonium hydroxid in excess, 
and allow to stand for some time, when the coloring matter will 
be precipitated with the aluminum hydroxid, Al(OH)3, leaving 
the solution colorless. 

In the iron process the water is brought in contact with 
spongy iron, and the result is the precipitation of ferric 
hydroxid, which carries down with it most of the organic 
matter. The precipitate may be removed either by sedi- 
mentation or by filtration through sand. 

Experiment 55. To a dilute solution of ferric chlorid, 
add an excess of ammonium hydroxid. The reddish brown 
precipitate of ferric hydroxid produced is similar to that in 
the iron process. 

Experiment 56. Pass a current of carbon dioxid through a 
dilute solution of calcium hydroxid till the precipitate at first 



98 SANITARY AND APPLIED CHEMISTRY 

formed is dissolved. Add to this solution an excess of limewater 
and notice the formation of the precipitate. 

WATER SUPPLIES OF CITIES 

It has been estimated that the daily allowance of water 
for each person for all purposes is from twelve to fifteen 
gallons a day. Among the poorer classes a very much 
smaller amount is actually used, for cleanliness is expen- 
sive. In American cities, however, the amount of water 
used per day per capita is very much larger, as shown by 
statistics compiled from the pumping records. It must 
be remembered, however, that this includes all the water 
used for manufacturing purposes, for lawn sprinkling, 
etc., and especially does it include the very large amount 
of water wasted every day by carelessness and by leaky 
supply pipes. It has been found that the introduction 
of water meters very appreciably lowers the per capita 
consumption. In American cities the amount used 
varies from 33 gallons to 320 gallons. 1 

In each locality local conditions must determine what 
is the most practical and safest source of supply. Of 
the possible sources mentioned on page 72 the following 
have been utilized. 

I. SURFACE WATER COLLECTED IN IMPOUNDING 
RESERVOIRS 

The following cities, among others, are supplied in 
this way : New York City, supplied by the Croton River 
and the Catskill watershed; Boston, supplied by Lake 
Cochituate; Newark, and Jersey City, New Jersey; 
Worcester, Cambridge, Springfield, Gloucester, and Lynn, 

1 " A Text Book of Hygiene," Rohe and Robin, p. 47. 



PURIFICATION OF WATER SUPPLIES 99 

Massachusetts ; New Haven, and Hartford, Connecticut ; 
Altoona, Pennsylvania ; Charleston, South Carolina ; 
Norfolk, Virginia ; Denver ; San Francisco, and Oakland. 
The catchment or collecting area, to be ideal, should 
be free from human habitation and covered with a forest 
growth. This is the case in respect to a few cities ; ordi- 
narily, however, there is a considerable population on 
the catchment area. Storage in these large reservoirs 
improves the quality of the water. Disease germs in 
our climate do not grow under these conditions and, if 
introduced, they are usually destroyed, because the 
length of time for which they can live under these condi- 
tions is limited, and the water is actually stored for quite 
a long time. 1 

II. WATER SUPPLIED BY SMALL LAKES 

There are a few cities that are supplied in this way. 
These lakes are really natural instead of artificial im- 
pounding reservoirs for the surface water. Rochester, 
New York, is supplied in this way from Hemlock Lake, 
and Syracuse, New York, from Skaneateles Lake ; Port- 
land, Maine, from Sebago Lake; and St. Paul, Minne- 
sota, from a number of small lakes. 

III. WATER SUPPLIED FROM THE GREAT LAKES 

The large cities supplied in this way are Chicago, Cleve- 
land, Buffalo, Detroit, Milwaukee, and Duluth. The 
chief difficulty with this source of this supply is that 
these cities discharge their sewage into the lakes, and 
although large sums of money have been expended in 
driving tunnels under the bed of the lake to a point five 
miles or more distant from the shore for an intake, yet 

1 " Clean Water and How to Get It," Hazen, p. 13. 



100 



SANITARY AND APPLIED CHEMISTRY 



in certain conditions of weather and temperature it is 
almost impossible to keep some sewage from getting into 
the water supply. 

IV. WATER SUPPLIED FROM RIVERS 

On account of convenient transportatiorTfacilities there 
is a tendency in this country for those cities built on large 
rivers to increase rapidly in population. It often becomes 
necessary, however, to obtain the water supply from the 
same stream. In the United States the following large 
cities, among others, are supplied from rivers : * 



Place 


Population 
1910 


Water from 
What River 


Drainage 

Area above 

Intake 

sq. miles 


Philadelphia . . . 

St. Louis .... 
Pittsburgh .... 
Cincinnati .... 


1,549,008 

687,029 
533,905 
363,591 


f Delaware 
1 Schuylkill 
Mississippi 
Allegheny 
Ohio 


8,186 

1,915 

700,663 

11,400 

72,400 


New Orleans . . . 
Washington . . . 
Minneapolis . . . 
Kansas City, Mo. . 
Indianapolis . . . 


339,075 
331,069 
201,408 

248,381 
233,650 


Mississippi 

Potomac 

Mississippi 

Missouri 

White 


1,261,084 

11,476 

19,585 

163,752 

1,820 


Providence . . . 
Louisville .... 

Toledo 

Richmond .... 
Paterson .... 


224,326 
223,928 
168,497 

127,628 
125,600 


Pawtuxet 

Ohio 

Maumee 

James 

Passaic 


91,000 

6,723 

6,800 

773 


Omaha 

Nashville .... 
Albany 


124,096 
110,364 
100,253 


Missouri 

Cumberland 

Hudson 


322,500 

12,800 

8,240 



1 " Clean Water and How to Get It," Hazen, p. 32. 



PURIFICATION OF WATER SUPPLIES 101 

If water of this kind must be used, it is necessary to 
install very complete purification works. If all cities 
were obliged by law to treat their sewage before they 
discharge it into the river, the problem of purification of 
a city supply would be very much simplified. It is, 
however, considered impractical to purify completely 
all the sewage entering into a stream, so a purification 
system for the water supply seems to be absolutely re- 
quired. 

V. GROUND WATER SUPPLY 

In many localities, and especially for the smaller cities, 
ground water is the most available and safest source of 
supply. In Brooklyn, most of the water supply of 142,- 
000,000 gallons daily is obtained from tubular wells 
driven in coarse ocean sand and gravel. In the vicinity 
of Brooklyn on Long Island and in New Jersey some 
other cities, notably Camden, New Jersey, are supplied 
in this way. Memphis, Tennessee, has been supplied 
in recent years by water drawn from sand and gravel 
deposits. Other cities that may be mentioned are 
Lowell, Massachusetts ; San Antonio, Texas ; Wichita and 
Topeka, Kansas; Jackson, Mississippi; and Winnipeg, 
Canada. Many European cities draw their water supply 
from wells. One of the most notable cases of this kind 
is Vienna, which has a population of 1,800,000. 

One disadvantage of ground water is that in localities 
where there is a limestone soil these waters are hard; 
in granite regions or where there is an abundance of gravel 
near the surface, the water may be soft. Another dis- 
advantage of ground water is that it frequently contains 
iron, which is removed by treatment and filtration, but 
with considerable difficulty. 



102 SANITARY AND APPLIED CHEMISTRY 

Ground water should be stored in dark reservoirs, as 
under these conditions the algae and other troublesome 
organisms, which injure the water, do not develop so 
rapidly. Surface water often improves in quality when 
stored in clean open reservoirs where the sides have been 
thoroughly cleared of vegetation. The effect of mud 
deposits in storage reservoirs is not necessarily harmful. 
If, however, these deposits furnish food for, and encourage 
the growth of, organisms that by their development 
impart a disagreeable taste and odor to the water, they 
should be removed. 



CHAPTER VII 
DISPOSAL OF SEWAGE AND GARBAGE 

The organic and inorganic material that accumulates 
as the waste of the modern city or from the country dwell- 
ing is of such a character that it must be quickly removed 
or it is a menace to the health of the inhabitants. This 
material is handled by the municipality at the common 
expense of the community, or in the isolated house it 
must be handled by the individual. It naturally divides 
itself into two general classes : first, the fluid and semi- 
fluid refuse which is generally disposed of by the " water- 
carriage " system, that is, it is flushed out by an excess 
of water under the name of " sewage " ; and second, the 
solid refuse which must be collected and carted to some 
central station to be disposed of and rendered innocuous. 
This is known as " garbage." 

In the water-carriage system of sewerage two systems 
have been in use — the combined and the separate. In 
the combined system all excreta, kitchen slops, waste 
water from baths and manufacturing establishments, 
as well as storm water, are carried off in the same conduits. 
In the separate system the storm water is carried off by 
surface or underground drains not connected with the 
sewers, which only discharge the refuse from the toilets, 
factories, and houses. There is a growing opinion among 
sanitary engineers that the best results are obtained in 
the use of the separate system. 

103 



104 SANITARY AND APPLIED CHEMISTRY 

SEWAGE 

Sewage may be defined as " a complex mixture, with 
water, of the waste products of life and industry from 
densely settled communities." The only solids of im- 
portance which this sewage carries are those which are 
susceptible of solution in water, or which become disin- 
tegrated in transit. Sewage consists very largely of water 
which acts as a vehicle to carry away a small quantity 
of other substances. In 1000 parts of sewage it is esti- 
mated that there is 1 part of mineral matter and 1 part 
of organic matter, leaving 998 parts of pure water. Now, 
the mineral matter contained in sewage is practically 
of no importance, so that all our efforts are directed toward 
the removal of the 1 part of organic matter in 1000 parts 
of water. The only really dangerous substances in sew- 
age are the disease-producing organisms, but the gases 
given off as the result of decomposition are extremely 
disagreeable and will, if breathed continuously, no doubt 
lower the vitality. Sewer gas is not as liable to contain 
microorganisms, which will be injurious to the health, 
as was formerly supposed. 

The material which issues from the sewers of large 
cities contains no dissolved oxygen and no oxidized nitro- 
gen. The reason for this is that the available oxygen 
of the water has been removed in oxidizing a portion of 
the carbon of the organic matter, but it has not sufficed, 
also, for the oxidation of the nitrogen, and further oxi- 
dation can go on only by the addition of more oxygen 
to the water. If the nitrogenous material in the sewage 
is represented by ammonia, then the following equation 
may be written : — 

2 NH 3 + 4 2 = 2 HN0 3 + 2 H 2 0. 



DISPOSAL OF SEWAGE AND GARBAGE 105 

Now this'nitric acid, coming in contact with the calcium 
carbonate of the soil and of the water, is decomposed 
thus : — 

CaC0 3 + 2HN0 3 = Ca(N0 3 ) 2 + H 2 + C0 2 . 

The most modern theory for the treatment of sewage is 
that it is carried on very largely by bacteria, and even 
this process of nitrification, as it is called, which the above 
equation represents, cannot go on without the interven- 
tion of nitrifying bacteria. This class of organisms 
must work in a medium containing a sufficient quantity 
of free oxygen. This treatment may take place in water, 
when there is a sufficient quantity of the free oxygen in 
proportion to the filth handled. In soil this nitrification 
is of the utmost importance in the process of preparing 
it for the growth of plants, and in keeping up its fertility. 

It * is not practical to purify sewage completely. Even 
in the most modern sewage treatment plants it often 
happens that the conditions are such that the effluent is 
very far below the standard for purified sewage. In 
other words, although the treatment removes a very 
large part of the foul putrescible matter that has an offen- 
sive smell and may remove a great proportion of the 
pathogenic germs, yet the purification cannot practi- 
cally be carried far enough to render the effluent safe to 
use as a water supply. The water of the stream contain- 
ing the treated sewage must itself be purified in a water- 
purification plant. 

The sewage may be disposed of : — 

1. By dilution. 

2. By irrigation. 

3. By intermittent filtration. 

4. By chemical precipitation. 

1 Geo. C. Whipple, Am. Jour. Pub. Health, Vol. Ill, p. 516. 



106 SANITARY AND APPLIED CHEMISTRY 

DISPOSAL OF SEWAGE BY DILUTION 

If the stream into which the sewage is poured is small, 
and the current of low velocity, the result will be the pro- 
duction of a very disagreeable odor from the decomposition 
of the sewage, but if, on the other hand, the flow of the 
stream is large, this sewage will be distributed through so 
much water that we shall not find any offensive odor 
arising from it. It has been estimated that a stream 
which carries off sewage should have a volume of from 
twenty-five to thirty-five times that of the sewage; the 
proportion, however, depends on the amount of free 
oxygen that is carried by the stream and several other 
factors. The amount of water needed to carry off the 
sewage can be calculated readily, by knowing the amount 
of water supplied to the town, as it has been found under 
normal conditions that the volume of sewage is practically 
the same as the amount of water supplied. 

In the case of the city of Milwaukee, as an illustration, 
for many years the sewage was turned into the Milwaukee 
River, a small stream, which became extremely foul, but 
arrangements were made to pump a large amount of water 
from the lake into the river 3| miles inland, thus supply- 
ing 26 times as much water as the volume of the sewage, 
and by so doing the sewage was flushed out with the 
water, and the odor disappeared. To handle the sewage 
of Chicago it would be necessary to follow the same plan, 
and have 25 times as much water in the drainage canal 
as the sewage of the city. 

The objection to the disposal of sewage in this way 
is, of course, the rendering of a river water so impure. 
Although some experimenters have argued that water 
after running 20 miles is quite completely purified by 



DISPOSAL OF SEWAGE AND GARBAGE 107 

the process of oxidation and nitrification, others claim 
that, even by running ten times as far, the pathogenic 
germs would not be removed, and there is a natural repug- 
nance against using, for drinking purposes, water that 
has been at any time contaminated by sewage unless it 
is purified by sand filtration. 

BROAD IRRIGATION OR SEWAGE FARMING 

Another method of disposal of sewage is by irrigation. 
There is a large amount of fertilizing material in the 
sewage of the modern city, and very persistent efforts 
have been made to utilize it economically. In America x 
this process has very little standing as an independent 
method of purifying sewage, especially in the more humid 
regions of the country. In Europe the process has been 
much more successful, but little financial profit has been 
made by sewage farming. The partial success abroad is 
no doubt due to favorable soil conditions, especially in 
Paris and Berlin, and to very careful and efficient manage- 
ment. In England broad irrigation is still practiced 
quite extensively, but in many locations it does not suc- 
ceed. The objections to the method that have been 
raised are the disagreeable odors in the vicinity of the 
farms, prejudice against the growing of vegetables by the 
use of sewage, and the transmission of disease germs by 
flies and other insects. 

INTERMITTENT FILTRATION 

The next method for disposal of sewage is by inter- 
mittent filtration. This process is a natural one, because 
it depends for its success upon the prevalence of certain 
natural conditions ; that is, the presence of oxygen and 

1 " Sewage Disposal," Fuller, p. 613. 



108 SANITAKY AND APPLIED CHEMISTRY 

living microorganisms. If we allow sewage to run, 
for some time, upon a filter bed composed of sand and 
gravel and then turn this sewage on to another filter 
bed and allow the water to run out of the first bed and the 
air to enter the spaces between the grains of sand, we 
furnish the conditions for the growth of the microorgan- 
isms. This is much more satisfactory than attempting 
to filter continuously through the same filter bed. As 
an illustration it was shown in one case that by the use 
of this process where 31,400 gal. of sewage per acre was 
filtered, 98.6% of the organic impurity was removed, 
and 99 % of the bacteria. 

THE SEPTIC TANK 

There is a modification of the above method which is 
known as the use of the septic tank, in which the sewage is 
liquefied by being stored first in the sunshine or in the air, 
allowing the aerobic bacteria to work, and afterward in a 
closed tank where another class of bacteria (the anaerobic) 
carry on their purifying process. This material is then 
run upon filter beds, and a very pure effluent is the result. 
Some engineers prefer to run the sewage first into a closed 
tank, through which it requires from 12 to 24 hours to 
pass, and where a thick scum covers the surface, gases 
are given off, and very complete decomposition takes 
place. The effluent from this tank is then run on to 
filter beds. It is to be noted that both aerobic bacteria, 
or those which work in light and air, and anaerobic bac- 
teria assist in the purification of sewage. 

THE IMHOF TANK 

The Imhof tank or Emscher-Brennen is another 
method of completing biological digestion of the solid 



DISPOSAL OF SEWAGE AND GARBAGE 109 

ingredients in sewage. The tank is in two compart- 
ments, the sewage flowing through an upper slotted trough 
at a rather slow rate, the solids settling out through the 
slots into the deep well below, where they are digested by 
anaerobic bacteria. The residual sludge is much smaller 
in volume than the sludge obtained from the septic tank ; 
it is slow to purify and much more easily dried. 

The Imhof tank or well has been adopted by Baltimore 
and Atlanta as preliminary treatment before going to 
biological filters. Many small towns are using it as a pre- 
liminary treatment of the sewage. It is more successful 
in general than the septic tank, as it removes more sus- 
pended matter from the sewage and gives an effluent 
easier to handle on the biological filter. 

THE ACTIVATED SLUDGE PROCESS 

The activated sludge process was developed by Fowler 
and his colleagues in England and consists essentially 
of blowing air, in finely divided bubbles, for several 
hours through raw sewage. This gives an opportunity 
for the aerobic, nitrifying bacteria to oxidize the putres- 
cible solids and soluble material over to innocuous nitro- 
gen compounds. This reaction will take place after a 
culture of the bacteria have been properly grown in what 
is known as activated sludge. (Activated sludge is the 
name given to the sludge that has been aerated for several 
days or until it contains nearly a pure culture of true 
aerobic nitrifying bacteria.) It is necessary, therefore, 
always to retain some of the sludge to start the treatment 
of each dosing of sewage. 

Many experiments have been carried out on inter- 
mittent and continuous methods, using this process, and 
it has been finally proven that a continuous process can 



110 SANITARY AND APPLIED CHEMISTRY 

be operated with satisfaction, giving almost perfect re- 
moval of putrescible solids and a very marked reduction 
of bacteria, the effluent being nonputrescible. Conse- 
quently, this is a complete method of sewage disposal. 

For many years, chemists and engineers have been 
trying to devise a means of recovering the nitrogen in 
sewage on a commercial basis. As the activated sludge 
is extraordinarily high in nitrates, it is a feasible proposi- 
tion to dry this sludge on a commercial basis and use it 
for a fertilizer. It has been shown at Milwaukee that 
it is probably possible to recover sufficient sludge to main- 
tain the cost of running the sewage disposal plant. . 

DISINFECTION OF SEWAGE 

Liquid chlorin and bleaching powder have been used 
to disinfect sewage where it was thought necessary to 
obtain an effluent not detrimental to the public health. 
Usually the liquid chlorin or bleaching powder is dosed 
into the sewage after it has been given some preliminary 
treatment. Ordinarily the effluent from biological tanks 
and filters is treated with about 3 parts per million of 
available chlorin. This destroys practically all the intes- 
tinal bacteria. In some instances raw sewage is treated 
with large quantities of free chlorin where sterilization 
is demanded, and no annoyance will be caused by intro- 
ducing the sewage so treated into a body of water. This 
method is utilized along the Atlantic coast in the vicinity 
of oyster beds. 

CHEMICAL PRECIPITATION OF SEWAGE 

Another method for sewage disposal is by chemical pre- 
cipitation. For this purpose such substances as ferrous 
sulfate, ferric sulfate, lime, or alum are used. It was 



DISPOSAL OF SEWAGE AND GARBAGE 111 

at first proposed to utilize the precipitated material as a 
fertilizer, and considerable money has been spent in pre- 
paring this material and extracting the water from it by- 
pressure. This process, however, has not been found to be 
very satisfactory, and improvements must be carried still 
farther before this method for disposal of sewage will be 
extensively adopted. 

To recapitulate, for the purification of sewage, we must 
depend largely upon the work of bacteria often in the pres- 
ence of oxygen, and any plan which utilizes the work of 
these organisms to the greatest extent, and furnishes the 
most complete conditions, for work in this way, will be 
successful. 

DISPOSAL OF HOUSEHOLD WASTE 

A method for economically disposing of garbage or 
household waste has long perplexed the health author- 
ities. Two conditions may be considered : that of dispos- 
ing of it by the householder on the premises where it is 
produced, and that of having it handled by the city 
authorities. 

Several methods have been used for disposal of refuse 
without removal from the premises. Among these the 
process of burning in the stove, range, or furnace, either 
with or without previous drying, is suggested. This is 
efficient and practical if the amount of such waste ma- 
terial is not too large, and if a good fire is maintained. 
In summer, when there is naturally a larger amount of 
refuse, and the fires are not kept burning so continuously, 
it is often difficult to handle garbage in this way. 

A modification of the above method consists in having 
an enlargement of the smoke pipe of the stove at the 
elbow, and to introduce into this, through an opening 



112 SANITAEY AND APPLIED CHEMISTRY 

in the side, a perforated basket containing the garbage. 
The material soon becomes dry and is partially charred, 
and then may be taken out and put into the stove, where 
it is useful as fuel. 

In some cities the plan of building brick or stone fur- 
naces in the yard, for the sole purpose of burning rubbish, 
has been adopted with great success. 

Another method of disposal is by burying in the soil, 
and as the decomposition takes place rapidly, if only a few 
inches of soil is placed over the material, no obnoxious 
odor arises to contaminate the air. When one hole is 
filled, it is covered and another is dug beside it ; but these 
holes must not be too deep or too large. 

MUNICIPAL REFUSE 

If the city or village undertakes to dispose of the gar- 
bage, usually great expense is incurred, as the quantity is 
very large. For instance, in Manhattan alone the dry 
refuse amounts to 1,000,000 tons in a year, and the gar- 
bage is 175,000 tons per year. 1 

Disposing of garbage to farmers for feeding of stock or 
swine is not very practical. This involves a long haul of 
ill-smelling material through the streets, and is particu- 
larly objectionable if the material is not collected every 
day. 

In some localities garbage is loaded on to scows, towed 
out to sea and dumped, but here the incoming tide may 
throw the decomposing material back on the shore. 

There is a very valid objection to using garbage, even 
if the more perishable material is excluded, for filling 
in the so-called " made land/' as decomposition will 

1 Price, "Handbook on Sanitation," p. 49. 



DISPOSAL OF SEWAGE AND GARBAGE 113 

continue for years in this soil, and the air of dwellings 
built upon it will be contaminated. 

Municipal refuse may be classified as follows :* garbage 
and small animals, ashes, general rubbish and manure 
and street sweepings. ,A common method of treatment 
is the reduction method, in which the grease amounting 
to 2 to 4 per cent is extracted by boiling under pres- 
sure, with naphtha and the " tankage " is used as a 
" filler " for artificial fertilizers or for fuel. Incineration 
may also be used by addition of combustible refuse with- 
out other fuel. Since in garbage there is often present 
from 15 to 30 per cent of partially burned coal ashes, 
it has some value as a fuel. Incineration in a suitable 
furnace seems to be the only satisfactory way to dispose 
of most general rubbish. This is the process used in 
Seattle, Richmond, New York, Milwaukee, and other 
cities. The heat is used for steam-making purposes and 
the clinkers are valuable for filling vacant lots. In 
1899, 81 communities in Great Britain were employing 
incineration as the chief means for disposal of refuse, 
and 76 of them turned the heat developed from the 
combustion of this refuse to some useful purpose, such as 
making steam to run electric lighting plants, for sewage 
pumping works, for grinding road material, and for use in 
the process of disinfection of clothing. 2 It is well to re- 
member that such quickly decomposing material as gar- 
bage should be immediately removed under sanitary 
inspection, whether any financial profit comes to the city 
from its treatment or otherwise. 

1 Rudolph Hering, Journal Am. Pub. Health Ass'n, Sept. 1910. 

2 Harrington, "Practical Hygiene," p. 509. 



CHAPTER VIII 
TEXTILES 

The textile industry makes use of a variety of raw 
materials, which ultimately are made into clothing, dra- 
peries, carpets, and rugs, as well as canvas, cordage, and 
similar products. These fibers are mainly of vegetable 
or animal origin. 

Those of vegetable origin are cotton, flax (linen), 
ramie, hemp, jute, and raffia, all made from the stem, 
bark, or bast fibers ; henequin or sisal, and manilla hemp 
used in making ropes and twine ; and fruit fibers, as 
cocoanut fiber, used especially for making brushes and 
mats. To this list should be added artificial silks and the 
artificial " fibers " which are all originally of vegetable 
origin. 

Those of animal origin are wool, hair, and silk. 

Mineral fibers are only used for special purposes, as 
asbestos for the manufacture of fire-proof fabrics. Some 
others are spun glass, mineral wool, and silver cloth. 

The fibers and the manufactured products are subjected 
to various complex processes of cleaning, bleaching, and 
dyeing, but nevertheless it is possible to distinguish the 
one from the other, both by microscopical and chemical 
methods. 

COTTON 

This consists, after purification, of nearly pure cellulose 
(C 6 Hio0 5 ) w . The raw fiber is mixed with and attached to 

114 



TEXTILES 115 

the seed in the pod or boll of the cotton plant. This seed 
is with difficulty separated from the cotton by the use 
of an ingenious mechanical contrivance called the cotton 
gin. The seeds have recently become of great commer- 
cial importance on account of the oil which they contain, 
and the cottonseed meal which is used as cattle food. 
(See p. 275.) The cotton fibers, when examined with 
a microscope, consist of long flattened tubes, thicker 
at the edges than the center, and spirally twisted. These 
fibers are usually not over an inch in length. The twisted 
structure not only assists in the identification, but it 
greatly facilitates spinning, as the fibers more readily 
interlock to form a thread. 

Experiment 57. Examine some cotton fibers by the use of 
a microscope magnifying from 150 to 300 diameters. A few 
fibers should be placed on the glass slide with a drop of water, 
and the cover glass carefully placed over them in such a way as 
to entirely exclude any air. 1 

Mercerized cotton is prepared as follows : The cotton is 
stretched on a frame and treated with a 30 % solution of 
sodium hydro xid, and afterwards well washed with water. 
By applying the soda solution to the stretched material, 
shrinkage, which would otherwise be about one fourth in 
length, is prevented, and at the same time the fibers are 
untwisted and acquire a high luster. The product is sup- 
posed to be a hydrated cellulose. Mercerized cotton is 
stronger than the untreated material, and takes hold of 
dyes more readily. 

Experiment 58. Test the action of alkalies on cotton by 
boiling for a few minutes some cotton goods in dilute sodium 
hydroxid solution. After cooling dip the goods in dilute acetic 

1 Woolman and McGowan, p. 279. 



116 SANITARY AND APPLIED CHEMISTRY 

acid and wash again. Compare the strength and appearance 
of this sample with another sample which has not been treated. 
Compare also experiments under Cellulose (p. 172). 

FLAX (Linen) 

The source of linen is the bast or inner bark fibers of 
the flax plant. The stalks, after being cut and stripped 
of their tops, seeds, and leaves, are laid in bundles in a 
pond where a fermentation process known as " retting " 
takes place. Under these conditions the water dissolves 
the connective tissue and soluble substances, and leaves 
the flax fibers. By a slower process the bundles of flax 
are spread on the grass and exposed to the action of the 
air, sunshine, and dew for a longer period. After the 
retting the fibers are subjected to mechanical processes 
known as " breaking " and " scutching," in which the 
woody parts of the stem are removed, leaving the clean 
fiber. The long fibers, known as the " line," are also 
separated from the shorter fibers, known as "tow." 
(The flax may or may not be bleached before spinning 
into threads.) 

The linen fibers are of quite different structure from 
those of cotton. They are long cylindrical fibers taper- 
ing to a point. Fine cross lines appear at intervals which 
give the appearance of joints or nodes. The fiber cells 
are pointed at the ends and polygonal in cross section. 

Experiment 59. Examine some linen fibers on a glass slide 
with a good microscope and compare with cotton fibers. Treat 
with iodine and again examine. 

Experiment 60. After freeing a sample of linen from dress- 
ing by boiling with a 3 % hydrochloric acid solution, treat with 
a 1% sodium carbonate solution, rinse with distilled water, 
and dry. Moisten the fringe on two adjacent edges, as obtained 



TEXTILES 117 

at a corner of the goods with olive oil or glycerine. Press 
between filter paper and place against a dark background. No- 
tice that with this treatment the linen fibers appear translucent, 
while cotton fibers, if present, appear opaque and white. 

WOOL 

The hair of the sheep, goat, or similar animal is of en- 
tirely different structure from those already described. 
This hair really consists of three distinct portions, 1 — 
the medulla, a central marrow, frequently containing the 
coloring matter of the wool; the fibrous cortical tissue, 
which gives the material most of its strength and elastic- 
ity ; and the epidermis of horny scales, which appear to 
be flattened cells overlapping one another like shingles. 
To the latter structure is due the characteristic " felting " 
property of wool. Different animals yield fibers of various 
length and thickness, and on their characteristics much 
of the different values depend. Ordinary wool fibers are 
from one to eight inches in length and -5^- to -^utu °f an 
inch in diameter. Raw wool contains frequently as 
much as 70% of impurities. These consist of "wool 
grease," " suint " or dried perspiration, mostly a po- 
tassium soap, vegetable and mineral dirt. These im- 
purities are removed from the wool by washing with a 
solution of sodium carbonate. After " carbonizing " to 
remove the vegetable matter, the wool is treated by the 
mechanical operations of carding, spinning, and weaving. 

Experiment 61. Examine some woolen fibers on the glass 
slide with a microscope. 

Experiment 62. In two porcelain evaporating dishes test 
samples of wool and of cotton by immersing them for 15 min- 
utes in concentrated sulfuric acid and in a 10% caustic soda 

1 " Household Chemistry," Snell, p. 219. 



118 SANITARY AND APPLIED CHEMISTRY 

solution. Remove the residue, wash, and examine. The sul- 
furic acid, while it dissolves cotton, causes the wool to become 
jellylike. With caustic soda the wool is dissolved and the cotton 
remains unchanged. 

SILK 

Silk is obtained from the cocoons of a caterpillar which 
feeds on the leaves of the mulberry tree. It differs from 
the other fibers described in having no cellular structure. 
The viscous fluid called fibrosin secreted by the glands 
of the caterpillar exudes in two streams which are after- 
wards united by a substance called sericin which is also 
secreted by the caterpillar. Under the microscope these 
two threads with their connecting masses are seen. These 
threads are from .0005 to .0007 inch in diameter and 
from 1300 to 1400 yards in length. About 75 % of the 
weight of the raw silk is fibrosin or silk fiber. proper and 
is separated by washing from the sericin which accom- 
panies it. 

Experiment 63. Examine a sample of raw silk on the slide 
under a microscope. 

Experiment 64. If silk (white silk thread) is treated with a 
40% solution of hydrochloric acid for two minutes, the silk is 
dissolved. 

ARTIFICIAL SILKS (Viscose) 

These products are made from some form of cellulose 
and are therefore originally of vegetable origin. For 
making pyroxylin silk, or Chardonnet silk, pure cellulose 
is converted into nitro-cellulose (see p. 171), and this is 
dissolved in ether and alcohol, making collodion. This 
pasty mass is then forced by great pressure through very 
small openings in a metallic plate into a warm chamber. 
The ether and alcohol soon evaporate and are recovered 



TEXTILES 119 

and used again as a solvent. The threads can be rolled 
on bobbins, but must be " denitrated " by immersing 
in a solution of sodium sulfid or ammonium sulfid. This 
takes away the highly inflammable quality of the nitro- 
cellulose, and the threads are ready for use. 

For making the cuprammonium silk, by Pauly's pro- 
cess, the cellulose is dissolved in an ammoniacal solution 
of copper hydroxid, and this is treated as in the previous 
process. This product is extensively used in Germany. 

In the viscose process, wood pulp is treated with a 
strong solution of caustic soda, and the soda-cellulose so 
formed is treated with carbon bisulfid. The product 
thus obtained, although soluble in water, is insoluble in 
alcohol and in brine. The viscous solution is forced 
through fine openings into a solution of common salt, 
which precipitates the material in fine threads. This 
viscose is decomposed by heat or by an ammonium chlorid 
solution into cellulose, which may be spun and dyed like 
silk. 

Experiment 65. Boil a sample of white artificial silk with 
a 4% solution of caustic potash, and it will be seen that the 
solution turns yellow. Pure silk treated in the same way leaves 
a colorless solution. Millon's reagent x also turns genuine silk 
red, while artificial silk is uncolored. 

Experiment 66. A Comparison of Textile Fibers. Burn a 
few threads of cotton, linen, wool, silk, and artificial silk and 
notice the difference in behavior. Vegetable fibers flash up 
and burn quickly, while the animal fibers burn slowly. Notice 
also the odor. 

Experiment 67. Ignite some of each of the fibers in a dry test 
tube. Notice the odor of the fumes which is characteristic. 

1 To prepare Millon's reagent, dissolve 100 grams of mercury in 71.5 
cc. of strong (1.4 sp. gr.) nitric acid in the cold. When chemical action 
ceases, add twice the volume of cold water. 



120 



SANITAKY AND APPLIED CHEMISTRY 



Red litmus paper moistened and held in the fumes will be 
colored blue if ammonia is given off, as when animal substances 
burn. A paper dipped in lead acetate will be colored brown 
by the fumes of hydrogen sulfid, when wool is heated in this 
way. With cotton or linen the fumes should color blue litmus 
paper red from the volatile acetic acid formed by the distilla- 
tion. With fabrics consisting of mixed fibers, the results of the 
above experiments are liable to be misleading. 

Experiment 68. To distinguish between wool and cotton, 
use white fabrics or threads of each. Place in porcelain dishes 
with Millon's reagent, and heat gently. It will be noticed that 
the vegetable fibers are unchanged in color, while the animal 
fibers become red. 

Experiment 69. Since linen is often adulterated with cotton, 
it is important to distinguish between these fibers. Use a fringed 
or frayed sample of the material, so as to get both the warp 
and woof. Place this in a porcelain dish and heat gently for 
two minutes in a 50% solution of caustic potash. Remove 
with a glass rod, wash, and dry between filter papers. The 
linen will be dark yellow in color and the cotton white or light 
yellow. 1 

In general it should be noted that with acids and alkalies 
the following reactions take place: 2 — 

Reactions with Alkalies 





Wool 


Silk 


Linen 


Cotton 


Strong 


Destroyed 


Destroyed less 


Fiber swells, 


Fiber swells, 


caustic 




rapidly 


becomes 


pale yellow 


alkalies 






brownish 
yellow 




Boiling 5 per 


Destroyed in 5 


Destroyed less 


Little effect if 


Same as linen 


cent 


mm. 


rapidly 


air is ex- 




NaOH or 






cluded 




KOH 










Cold 10 per 


Little effect 


Little effect 


No effect 


No effect 


cent 










NH 4 OH or 










(NH 4 ) 2 C0 3 











1 Adapted from Woolman and McGowan, pp. 296-297. 

2 " Shelter and Clothing," Kinne and Cooley, p. 197. 



TEXTILES 
Reactions with Acids 



121 





Wool 


Silk 


Linen 


Cotton 


Cone. H2SO4 


Succumbs slowly 


Destroyed 


Soon dissolves 


Dissolves more 




on heating or 


with yellow 




quickly 




drying on fiber 


color in 2 
min. 




than linen 


Strong HNOs 


Becomes yellow 


Same color 


Not colored ; 


Same as linen 




(xanthoproteic 


effect as 


dissolves 






reaction) . 


wool ; dis- 


slowly in hot 






Dissolves 


solves 


solution ; 






slowly 


quickly 


nitrates in 
cold 




Strong HC1 


Hardly affected 


25 per cent so- 


Dissolved very 


Action quicker 






lution con- 


slowly by 


than with 






tracts fiber; 


concentra- 


linen 






30 per cent 


tion 








dissolves in 










10 min. ; 40 










per cent dis- 










solves in 2 










min. 






Picric acid 


Yellow 


Yellow 







The problem of differentiating between various textile 
fibers is much complicated by the various processes to 
which the goods are subjected in preparing them for 
the market. These include bleaching, especially with 
sulfur dioxid and chlorin; dyeing, with a great variety 
of colors, both of vegetable origin and those made from 
coal tar; weighting, a process applied especially to silks 
which not only adds greatly to the weight of the goods, 
but loads them with numerous chemicals; dressing and 
sizing with starch, glue, dextrin, etc., and finally finishing. 



FIRE-PROOFING COTTON 



After long investigation William H. Perkin, an English- 
man, has succeeded in devising a process for rendering 
cotton fire-proof. This process was patented in the United 



122 SANITARY AND APPLIED CHEMISTRY 

States in 1907. It is especially valuable for use on cotton- 
flannel and flannelette, and fabrics of that class, which, 
on account of the raised nap, are exceedingly inflammable. 
The material is first run through a solution of sodium 
stannate, of 1.22 sp. gr., so as to become thoroughly 
impregnated, and the excess of this solution is squeezed 
out. It is then dried by passing over heated copper 
drums, and afterwards run through a solution of ammo- 
nium sulfate of 1.75 sp. gr., again squeezed and dried. The 
soluble sodium sulfate which remains in the goods is 
then washed out, the material is dried and finished by 
ordinary methods. This very valuable process should 
be used more commonly for children's clothing, and in 
any case where. there is danger that clothing may take fire. 
For further details on textiles, or for methods of 
quantitative textile analysis, the student is referred to 
Bulletin No. 9, Department of Agriculture; " Textile Fi- 
bers/' Matthews; "Textiles," Woolman and McGowan; 
" Shelter and Clothing," Kinne and Cooley ; " Elementary 
Household Chemistry/' Snell ; " Chemistry of Familiar 
Things," Sadtler; " Municipal Chemistry/' Baskerville; 
" Chemistry of the Home," Weed ; "Chemistry of Com- 
mon Things," Brownlee; "The Story of Textiles," Wal- 
ton ; " Laboratory Manual of Dyeing and Textiles," 
Matthews; "Textiles," A. F. Barker; and "Household 
Textiles," Gibbs. 



CHAPTER IX 
CLEANING: SOAP, BLUING, BLEACHING 

With our modern knowledge of the means of trans- 
mitting disease, filth is something to be avoided, as it 
assists in the spread of infection from one locality to 
another. The love of cleanliness, which is considered 
a sign of a higher civilization, is, no doubt, the outgrowth 
of years of experience with the dangers of dirt. This 
abhorrence for filth is a sanitary safeguard : it protects 
the body, the air, the water supply, and the food supply. 
As man has advanced he has demanded some cleansing 
agent for the body, the utensils, and the clothing, and so 
great industries have developed for the preparation of 
these agents. 

Substances used for cleaning act either mechanically or 
chemically to remove the offensive materials. In the 
use of soap and sand, for scouring, there is a combination 
of these methods ; and, in fact, when the chemical loosens 
up the fibers or sets free the dirt, some mechanical process 
is often required to remove it. 

Most of the polishing and cleaning powders on the 
market depend, for their efficiency, upon the action of a 
very finely divided substance like silica, precipitated 
chalk, or rouge. This is mixed with some fat or oil; 
thus, some " Putz Pomades " contain rouge, finely divided 
silica, and a perfumed fat. In the choice of a polishing 

123 



124 SANITARY AND APPLIED CHEMISTRY 

material, one should be selected that is so finely divided 
that it will not scratch the metal. Dry sodium bicar- 
bonate (baking soda) can be safely used for cleaning and 
polishing. Rejected Welsbach mantles are also well 
adapted for this purpose. 

To remove a stain, the process selected depends on the 
character of the stain. It may be dissolved, absorbed, 
bleached, or neutralized. 

Borax, Na2B 4 7 , added to water, greatly aids in the 
removal of dirt, in special cases. Ammonium hydroxid 
(aqua ammonia) is also used for the same purpose, and, 
as it forms a soap with the oily matters of the skin or of 
the fabrics washed, it is a convenient cleaning agent. A 
teaspoonful of ammonia to a quart of water is an excellent 
wash for woodwork, and may be used to brighten carpets 
or rugs. Much of the " household ammonia " on the 
market is of a very low grade, and so it is always advisable 
to purchase ammonia from a druggist. 

A cleaning material should not only remove the grease 
or dirt, but it must be of such a nature that it will not 
injure the article cleaned. From the work of Mrs. 
Richards, 1 many of the following suggestions are taken. 

In some cases, as with wood, leather, metal, etc., the 
dirt does not penetrate into the interior, but remains 
on the surface ; in other cases the whole fabric is filled with 
dust and grease. All polished wood surfaces, except those 
finished with wax, may be cleaned with a weak solution of 
ammonia, or soap, but they should never be treated with 
a strong alkali. 

As solvents for grease, either kerosene or turpentine 
may be used, and should be applied with a soft cloth. 
Painted surfaces, especially if white, may be cleaned with 

1 Richards and Elliott, "The Chemistry of Cooking and Cleaning." 



cleaning: soap, bluing, bleaching 125 

a little " whiting/ ' CaC0 3 , which can be applied with a 
piece of cheesecloth. The wood is afterward washed 
with water and wiped dry. Painted walls, if painted with 
oil paints, can be cleaned in the same way, but " tinted " 
walls, since water colors are used, are disfigured by this 
treatment. 

Leather may be kept bright and clean by the use of 
kerosene, or occasionally a little oil. Marble may be 
scoured with sand soap, and finally polished with a coarse 
flannel. It should not be forgotten that marble is cal- 
cium carbonate, CaC0 3 , and consequently should never 
be treated with an acid, or even an acid fruit juice like 
lemon juice. Metals can usually be cleaned with a hot 
alkaline solution or a little kerosene. To clean glass, 
it may be covered with a paste of whiting, ammonia, 
and water, and after it is dry this may be rubbed off with 
a woolen cloth or with paper. Kerosene is excellent 
for this purpose, especially in the winter when the water 
would freeze. 

Household fabrics are often washed with alkaline solu- 
tions or with soap. In some cases naphtha may be used 
for washing such fabrics. As some of the solvents, such 
as naphtha, benzine, turpentine, and gasoline are fre- 
quently used for cleaning, and removing grease, it is 
extremely important to remember that they are all very 
volatile, and that the vapors may take fire from a lamp, 
gas jet, or stove, even if at some distance. On this account 
work of this kind should be done by daylight and out of 
doors, if possible. Many serious burns occur from lack 
of these precautions. Carbon tetrachlorid (CC1 4 ) has 
been recently used in the place of benzine, and has the 
advantage of being incombustible, and of being nearly 
odorless. It may also be used to mix with gasoline. In 



126 SANITARY AND APPLIED CHEMISTRY 

the use of the volatile solvents like gasoline, enough 
should be used to cover a large portion of the goods. 

To remove stains, spots, and tarnish, a little knowledge 
of chemistry will serve an excellent purpose. Since grease 
is readily absorbed by blotting paper, spots may often 
be removed from fabrics by placing the goods between 
two pieces of blotting paper, and then heating with a warm 
iron. French chalk will sometimes absorb the grease, 
especially if the spots are fresh. Grease may also be 
removed by the use of hot water and soap, ammonia, or 
even borax. If there is danger that these solvents will 
injure the goods or the colors, it is better to use some sol- 
vent such as chloroform, ether, alcohol, turpentine, ben- 
zine, or naphtha. Ether and chloroform are better 
adapted to the more delicate fabrics. " The trouble- 
some ' dust spot ' has usually a neglected grease spot for 
its foundation. After the grease is dissolved, the dust 
must be cleaned out by thorough rinsing with fresh 
liquid or by brushing after the spot is dry." 1 

Since paints consist of oil and some coloring matter and 
lead or zinc oxids, paint spots should be treated with a 
solvent for the oil, and then the coloring matter can be 
brushed off. Fresh spots may be treated with turpentine, 
benzine, naphtha, or gasoline, but old paint spots must 
be softened with oil or grease, and may then be removed 
by the appropriate solvent. Pitch, tar, or varnish may 
be treated with oil, and then be dissolved out with tur- 
pentine. Paraffin is most readily removed from clothing 
by putting blotting paper over the spot and melting it 
with a hot iron. The paper will absorb the melted 
paraffin. 

Sugar deposits are soluble in warm water. If acids have 

1 Richards and Elliott, loc. ciU 



CLEANING: SOAP, BLUING, BLEACHING 127 

destroyed the color of goods, this may usually be restored 
by ammonia, and dilute alcohol may sometimes be used 
in the same way for the stains from fruit. 

Ink spots would not be so difficult to remove if we knew 
in advance the composition of the ink. Fresh ink usually 
dissolves in cold water, though sometimes sour milk or 
lemon juice is more efficient. Ink stains may also be 
removed with blotting paper or some absorbent. Ink 
stains on marble may be treated with turpentine, baking 
soda, or strong alkalies, or a paste may be made with the 
alkali and turpentine, and this may be left for some time 
in contact with the spot, and finally washed off with water. 
A dilute solution of oxalic acid may often be successfully 
used to remove either ink stains or iron-rust spots. 

If there is much iron in the water supply, this stain 
may be removed from bowls or other porcelain ware by 
the use of hydrochloric acid, then rinse with water, and 
finally with a solution of soda. The addition of one per 
cent of formaldehyde very greatly reduces the action of 
the acid on iron pipes. 

Silver is readily tarnished by sulfur, either from eggs, 
or from rubber bands or elastic, or sometimes from the 
sulfur compounds in the illuminating gas. The sulfid of 
silver thus formed is grayish to black. Silver thus tar- 
nished should be rubbed with moist common salt before 
washing, thus forming a silver chlorid, which is then 
washed in ammonia, in which it is soluble. Another 
common method of cleaning silver is to boil the silver 
ware in a porcelain-lined kettle with a piece of sheet 
aluminum, and a little soda and salt. The articles are 
then rubbed slightly with a soft cloth. 

For cleaning and polishing brass and copper, nothing is 
better than oil and rotten-stone, and most of the good 



128 SANITARY AND APPLIED CHEMISTRY 

polishes on the market are made from these materials, 
with alcohol, turpentine, or soap. Kerosene is useful in 
keeping metals bright, as well as glass and wood. Alu- 
minum may be cleaned by the use of whiting or any silver 
polish, but alkalies should not be used upon this metal. 
Aluminum does not readily tarnish. As it does not rust, 
with ordinary care it will, in a kitchen utensil, last for 
many years. Iron-rust stains may often be completely 
removed from delicate fabrics by the use of lemon juice 
and common salt. 

Experiment 70. To remove an iron-rust spot from a piece 
of goods, stretch the cloth over a dish containing hot water, 
then as the steam arises and the goods becomes moist, drop 
a little muriatic acid, HC1, upon the rust spot with a medi- 
cine dropper; after a moment lower it into the water. If 
the spot is not removed, repeat the operation, then rinse in 
clear water, and finally in a dilute solution of ammonia to 
neutralize any acid that might remain and injure the goods. 1 

SOAP 

Water, and a few other solvents, are used to remove 
dirt, or, as it is sometimes called, " matter out of place. " 
Some of these foreign substances readily dissolve in the 
water ; others, like the fats, will dissolve in ether or gaso- 
line ; and still others, as the resins, will dissolve in alcohol. 
Some form of alkali, such as wood ashes, was formerly 
used with the water, to assist in removing the dirt. It 
was found, however, that this had a very destructive 
action on the goods, so a " saponified " fat, the product 
produced by the action of an alkali on a fat, or what we 
call soap, came into use. This, when well made, does not 
injure the goods. Soap was used instead of the lye from 

1 Richards and Elliott. 



cleaning; soap, bluing, bleaching 129 

the lixiviation of ashes, long before the chemistry of the 
process became known. It was not till 1813 that Chevreul 
published his scientific researches on the composition 
of fats and the process of soap-making. 

The raw materials used in soap manufacture are a fat 
and an alkali known as " caustic alkali/ ' which may be 
either sodium hydroxid (NaOH), which makes a hard 
soap, or potassium hydroxid (KOH), which makes a soft 
soap. These are made by boiling the carbonate with 
slaked lime, in accordance with the equation : — 

Na 2 C0 3 + Ca(OH) 2 = CaC0 3 + 2 NaOH. 

From this mixture the calcium carbonate settles out, 
and the solution of the caustic alkali is boiled down to a 
solid, and is put upon the market under the name of 
" concentrated lye," or the concentrated solution is used 
directly by the soap maker. 

More recently caustic soda has been made directly 
by the electrolysis of sodium chlorid, NaCl. The sodium 
deposited at one pole is dissolved in water, and the chlorin 
is used for making bleaching powder. 

The other ingredient of a soap is either a vegetable or 
animal fat or oil or a resin. Such oils as that of palm nut, 
cocoanut, olive, hemp seed, linseed, cottonseed, fish, or 
lard may be used, and fats like beef tallow, mutton tallow, 
lard, or house grease. 

SAPONIFICATION 

The process of " saponification " may be brought about 
either by the action of water or steam at high temperature 
and pressure (especially in the presence of a dilute mineral 
acid), by the action of caustic alkalies, or sometimes by 
the use of lime (see Candles, p. 56). 



130 SANITARY AND APPLIED CHEMISTRY 

The fats may be briefly described as consisting of ethers 
of the triatomic alcohol-radicle, containing glycyl, C 3 H 5 . 
By treatment with alkalies or high-pressure steam, they 
yield glycyl alcohol (glycerin) and stearic or other fatty 
acid. 1 

The name given to the compound of the acid and 
glycerin is stearin, palmitin, or olein. In the case of 
stearin, the saponification equation would be : — 

C 3 H 5 (C 18 H 35 2 )3 + 3 KOH = C 3 H 5 (OH) 3 + 3 KC 18 H 35 2 . 

Stearin Caustic Potash Glycerin Soap 

With palmitin or olein, the reaction is similar. If the 
fat or oil is solid, it contains a preponderance of stearin or 
palmitin, but, if liquid, there is an excess of olein. 

In making soap on a large scale, 2 a kettle, provided with 
both a closed and open steam coil, so that the soap may be 
boiled either by the heat or the free steam, is used. A ket- 
tle that will hold 100,000 lb. of soap is 15 ft. in diameter 
and 21 ft. high, and is made of f in. boiler plate. The 
melted fat and lye are run into the kettle and mixed by 
the aid of free steam and boiled for some time, or until 
the soap has a dry, firm feel between the fingers ; it is then 
" salted out " by adding common salt. In boiling, the 
saponification represented in the above equation has 
taken place, and when salt is added this causes the soap 
to separate from the caustic lye and glycerin. After 
boiling, to mix thoroughly, the mass is allowed to stand 
in the kettle until the soap rises to the top, and then the 
lye may be drawn off at the bottom of the kettle. Some 
more strong lye is then added, and the boiling is continued 
till the material is fully saponified, which the experi- 

1 Allen, "Commercial Organic Analysis," p. 183. 

2 Thorp, "Outlines of Industrial Chemistry," p. 340. 



cleaning: soap, bluing, bleaching 131 

enced soap boiler knows by sight, feel, and taste, and then 
the contents of the kettle is again allowed to stand for 
a while, and the additional lye is drawn off. The soap 
is then boiled with some water, and is allowed to settle 
again, to facilitate the separation of more alkali, dirt, and 
impurities, called " nigre." After standing several days, 
the soap is pumped into the " crutcher," which consists 
of a broad, vertical screw working within a cylinder, 
which is placed in a larger tank. Here it is thoroughly 
mixed, and any perfume or scouring material may be 
added. The soap is then drawn off into rectangular 
" frames," holding about 1000 lb., where it is allowed to 
solidify. The sides of these frames are removed and the 
soap is cut, by means of a wire, into slabs and then into 
bars. If put on the market in the form of cakes, the bars 
are afterwards pressed into the desired shape. 

" Half -boiled " soaps are made in the " crutcher, " 
by heating the stock to 160° F., and allowing it to stand 
for some time. It is evident that all the glycerin remains 
in a soap of this character. 1 

For making white soaps, tallow, palm oil, and cocoanut 
oil are used. Castile soap, if genuine, is made from olive 
oil, sometimes with the addition of cocoanut or rape seed 
oil. It is useless to attempt to make a good soap out of 
inferior material. In making lower grades of soap, cheaper 
fats are used, and frequently those that have a rancid 
odor. This is sometimes " corrected " by the addition 
of a strong perfume, like oil of " mirbane," — nitroben- 
zene, made from coal tar. Yellow soaps almost always 
contain considerable rosin; that is, they are made by 
the usual process, except that quite a large proportion 
of rosin is used to replace the fat. This has valuable 

1 " Industrial Chemistry," Rogers- Aubert, p. 575. 



132 SANITARY AND APPLIED CHEMISTRY 

soap-making qualities, and would not be classified as 
an adulterant of soap. Cocoanut oil saponifies with- 
out boiling, so it is used in making the " cold process " 
soap. This material also admits of the use of a larger 
quantity of water, so that the soap will be hard and still 
contain as much as 70% of water. Soap is mottled by 
stirring into it, while warm, some coloring substance, 
such as copperas, ultramarine, or an aniline color. This 
does not in any way improve its quality. 

Sand soap, pumice soap, and products of a similar 
character are made by incorporating sand, " volcanic 
ash," or powdered pumice, with the ground soap. 
These substances can act only mechanically; that is, 
they sandpaper off the dirt. Some of the most widely 
advertised cleaners consist of from 50 to 90 % of " vol- 
canic ash " or powdered feldspar, mixed with some pow- 
dered soap and alkali. A silicated soap is made by mixing 
with the ordinary soap some silicate of soda or soluble 
glass, as it is called. Into most laundry soaps both 
sodium silicate and sodium carbonate are " crutched," 
as a filler to soften hard water and to give additional 
detergent properties. 

Toilet soap is made either by melting raw soap, by per- 
fuming an odorless soap, after cutting in fine shavings and 
drying, or by making the soap directly by the use of pure 
materials. In either case the mass is colored by metallic 
oxides or aniline colors, and is perfumed by the use of 
essential oils, and then it is pressed into molds while 
yet fresh. Recent tests show that good toilet soaps 
that are made by some of the standard manufacturers 
cost the purchaser from 20 to 30 cents per pound for the 
actual soap bought. Fancy brands, especially those which 
are imported, cost from 50 cents to $1.40 per pound. 



CLEANING: SOAP, BLUING, BLEACHING 133 

" Floating soap " is made by simply running the 
" crutcher " at a high rate of speed, thus entangling con- 
siderable air with the soap, and so lowering the specific 
gravity of the mass until it floats. 

The use of a large proportion of cocoanut oil in soap 
facilitates saponification and tends to make a soap that 
can be used with salty water without curdling. Some 
" marine " soaps are made in this way, also shaving 
soaps. 

To make a transparent soap it is necessary to dissolve 
an ordinary soap in alcohol, allow the insoluble residue to 
settle out, and distill the alcoholic solution to jelly. This 
may then be pressed into molds and dried. Another 
method very frequently employed is to make a cold process 
soap, with coloring matter and perfume added, and then 
to add to the mass more glycerin, or a strong sugar solu- 
tion, which renders it still more transparent. 

Soft soap is made directly by the use of potash lye, or 
by the use of soda lye and considerable water. The 
glycerin and the excess of lye, if any, remain in the soft 
soap. This is used in " fulling " or shrinking cloth and 
in other manufacturing operations, probably on account 
of the excess of alkali which it contains. 



GLYCERIN 

The salt lye which is drawn off from the kettle in which 
soap is boiled is used for the manufacture of glycerin. In 
this process the soluble soap and impurities are taken out 
by chemical treatment, and mineral salts are separated 
by evaporation and crystallization. The purified crude 
residue containing about 80% glycerin is distilled with 
steam under diminished pressure. 



134 SANITARY AND APPLIED CHEMISTRY 

It is not economy to use a cheap soap, as on account of 
the excess of alkali which it usually contains it injures the 
fabrics washed, by causing the fibers to disintegrate and 
readily fall apart. 

There is a great advantage in using a well-dried soap, 
as it does not so readily become soft in the water and 
therefore does not wash away so quickly. A laundry soap 
will lose 25 % of water if the bars are piled and allowed 
to remain for some time where they are freely exposed to 
the air. 

In his researches on soap, Chevreul said that the clean- 
ing action was because the soap was decomposed, when 
brought in contact with water, into fatty acid and alkali. 
The impurities are set free by the alkali and entangled 
by the fat acid salts, and thus removed with the lather. 
Thus it will be seen that vigorous rubbing is not necessary 
to remove the dirt, though, of course, it aids the process. 

Ordinary soaps are readily soluble in water, but if the 
water is " hard " from the presence of lime or similar 
mineral substances, the alkali soap is decomposed and an 
insoluble lime soap is precipitated, thus forming a dis- 
agreeable scum on the water. Not until all this lime is 
thrown down by the soap will the latter begin to have a 
detergent action. 

The equation for the formation of the lime soap would 
be: — 

2 C 18 H 35 2 Na + CaS0 4 = Ca(Ci 8 H3 5 2 )2 + Na 2 S0 4 . 

On account of the necessity for using hard water in some 
localities " washing soda " Na 2 C0 2 + 10 H 2 is used to 
" break " the water ; that is, to precipitate the lime so 
that less soap will be required, thus : — 

CaH 2 (C0 3 ) 2 + Na 2 C0 3 = CaC0 3 + 2 NaHC0 3 . 



CLEANING: SOAP, BLUING, BLEACHING 135 

(See Hard water, p. 77.) 

In order to make a laundry soap fit for use with hard 
water, sodium carbonate is added to it in the crutching. 

Experiment 71. To make a hard soap, dissolve in a medium- 
sized beaker 15 grams of caustic soda (sticks) in 120 cc. of water, 
and pour one half of this into a porcelain evaporating dish of 
at least 500 cc. capacity ; add 60 cc. of water and 50 grams of 
tallow. Boil this solution for three quarters of an hour, care- 
fully replacing, from time to time, the water that has been lost 
by evaporation; then add the remainder of the solution of 
caustic soda and boil for at least an hour more. Water should 
be added as before, but the volume of the liquid may be allowed 
to decrease about one third. Add 20 grams of salt, boil for a 
few minutes, and allow the liquid to cool. The soap will rise 
to the top, and the glycerin, excess of lye, and salt will remain in 
solution. 

Experiment 72. Slightly acidify the water solution sepa- 
rated from the soap in the above experiment with dilute hydro- 
chloric acid. If any fatty acids or impurities separate out, 
filter. Pour the solution into a porcelain evaporating dish, 
and evaporate to dryness on a water bath. Dissolve the residue 
in strong alcohol, filter or decant from the undissolved crystals 
of salt, and evaporate the alcohol. The slight residue will be 
sticky, and give the sweet taste of glycerin. 

Experiment 73. Cut a good quality of soap into shavings 
and mix with hot water on a water bath, until well dissolved. 
Add dilute sulfuric acid until the solution is acid. Note that 
if the soap is " filled/ ' the sodium carbonate will cause an efferves- 
cence on adding acid. Heat on the water bath for some time 
or boil slowly, and the fatty acid will separate, forming an oily 
layer on the top. When clear this may be separated from the 
water by pouring on a wet filter, and the sulfuric acid removed 
from it by washing on the filter with hot water. 

Experiment 74. To determine the water in soap, weigh 
5 grams of shaved soap in a shallow aluminum dish, and heat it 
in the drying oven for several hours. By weighing again the 
percentage of loss, shows the water originally present. 



136 SANITARY AND APPLIED CHEMISTRY 

SOAP POWDERS 

Washing soda, Na2C03lO H 2 0, is often used, not only 
to soften hard water, but as a stronger washing agent than 
soap. This is a much better material than most of the 
so-called washing powders of the grocer. It should always 
be dissolved in a bottle or other vessel, and used as a solu- 
tion in the quantities necessary. An excess disintegrates 
the fabrics, or "rots'' the goods. Sometimes the washing 
powders or liquids on the market contain, in addition to 
the washing soda, a little soap or ammonium carbonate 
or a small per cent of borax, but they are much more 
expensive than the common washing soda, and no more 
efficient. Oxalic acid (H2O2C2O2), is often used in laun- 
dries, to whiten the goods by neutralizing the excess of 
alkali. This practice causes the rapid destruction of the 
fabric so treated. 

Experiment 75. To test a washing powder for sodium car- 
bonate, put a little of it in a test tube and add a few drops 
of hydrochloric acid. If there is a brisk effervescence, it will 
indicate the presence of a carbonate, and if the gas that is 
given off colors the flame of a Bunsen burner yellow, it indicates 
sodium. 

BLUING 

Bluing is the process resorted to in the laundry to over- 
come the slight yellow color of the clothes, and for the 
same purpose in the bleacheries where new goods are 
finished. 

Indigo was one of the substances most commonly used 
some years ago. It was known to the ancient Egyptians 
as a dye and to the Romans as a pigment. The method 
of using it for bluing, as it is insoluble in water, is to tie up 
a lump in a cloth, and when soaked in water the finely 



cleaning: soap, bluing, bleaching 137 

divided precipitate which is in suspension will give a blue 
color to the water, and to the clothes, which are immersed 
in it. 

Prussian blue (ferric ferrocyanid), Fe 4 (Fe(CN) 6 ) 3 , is also 
used for bluing. It is insoluble in water and in mineral 
acids, but is decomposed by alkalies and dissolved by 
oxalic acid. It is generally used as a solution or " liquid 
blue," but this imparts to the goods a greenish blue color. 
On account of the ease with which it is decomposed by 
alkalies, there is danger that " iron rust " will be deposited 
on the goods if this form of blue is used. 

Experiment 76. Make Prussian blue by the action of 
ferric chlorid, FeCl3, upon potassium ferrocyanid, K 4 Fe(CN) 6 , 
in the presence of a few drops of hydrochloric acid. Treat 
this blue precipitate with an excess of sodium hydroxid, and 
heat to boiling. Notice the reddish brown precipitate of ferric 
hydrate, Fe(OH) 3 . 

Experiment 77. Make some Prussian blue, as in the pre- 
vious experiment, and add to the precipitate, in the test tube, 
a few crystals of oxalic acid, and warm the mixture. Notice 
the intense blue solution obtained (liquid blue). 

Ultramarine is an interesting artificial compound which 
is put upon the market in the shape of small " bluing 
balls." It is similar to the native mineral called " lapis 
lazuli," and is a double silicate of sodium and aluminum 
containing sulfur. Like indigo, it is insoluble in water 
and is simply held in suspension in that liquid. There is 
difficulty in preventing the formation of blue spots and 
streaks with the solid blue. This blue is extensively used 
for coloring wall paper and for " bluing " white sugar. 

Experiment 78. To show the presence of sulfur in ultra- 
marine, place a part of a bluing ball in water in a test tube, 



138 SANITARY AND APPLIED CHEMISTRY 

and add to it enough hydrochloric acid to make the solution 
acid. Notice the odor of escaping gas when the solution is 
warmed, and test it for hydrogen sulfid, by holding in the gas 
a paper dipped in lead acetate solution. The paper turns 
black on account of the formation of lead sulfid. 

Aniline colors made from coal tar are the basis of most 
of the liquid blues on the market at the present time. 
The soluble blues from this source are very numerous, 
and they are probably as satisfactory as anything for the 
purpose. 

BLEACHING 

At the present time neither bleaching nor dyeing is 
often carried on in the household. Large establishments 
are fully equipped for this work so that there is usually 
no reason for attempting it on a small scale. 

The object of bleaching is to convert the color-bearing 
compound into a colorless product. In textiles the color 
is either of vegetable or animal origin. These colors 
may be removed either by a process of oxidation or by 
a process of reduction, and the agents used naturally 
divide themselves into these two classes. 

Some of the oxidizing agents used are Calcium hypo- 
chlorite, Sodium hypochlorite, and Hydrogen peroxid. 
The bleaching of linen or cotton when it is spread on the 
grass and frequently sprinkled, is an application of the 
slow oxidizing property of the air. Chlorin is the active 
bleaching agent of the hypochlorites. These are used 
for linen and cotton goods, but not for silk or woolen 
fabrics. Hydrogen peroxid (H 2 2 ) in acting as an oxidiz- 
ing agent gives up half of its oxygen, with the formation 
of water. The common commercial hydrogen peroxid 
is a 3 % solution in water, and is quite unstable. It is 






cleaninq: soap, bluing, bleaching 139 

useful as a milder bleach than the others mentioned and 
is used especially in bleaching hair, feathers, and ivory. 

The chief reducing substance used in bleaching is sulfur 
dioxid (SO2). It is generally used as a gas, and is 
formed whenever sulfur is burned in the air. The goods, 
as straw hats, woolens, or silks, are moistened and sus- 
pended in the vapor of S0 2 . A dilute solution of sodium 
bisulfite, acidified with hydrochloric acid, may also be 
used for soaking the goods. 



CHAPTER X 
DISINFECTANTS, ANTISEPTICS, AND DEODORANTS 

Since the health of the body depends so largely upon 
sanitary surroundings, it is important to consider what 
assistance modern science can offer to bring about the 
most hygienic conditions in the household. Infection, 
in general terms, is something capable of producing disease 
that comes to the body from without, and this infection 
usually reaches the system by the aid of certain lower 
forms of life known as microorganisms. These micro- 
organisms may be distributed by impure water, by house 
flies, by flying dust, or by personal contact between indi- 
viduals. We may try to check the progress of a disease 
within the body, where it is often a difficult problem. It 
is better to attempt to prevent the disease from invading 
the body by keeping the dangerous microbes out, or de- 
stroying them before they have an opportunity to enter. 
Those substances which are capable of checking the growth 
of the microorganisms, but without necessarily killing 
them, are known as " antiseptics " ; so all " disinfectants/' 
or destroyers of infection, are also antiseptics, but antisep- 
tics are not necessarily disinfectants. The surgeon of 
to-day deals with wounds in such a way as to have the 
conditions aseptic, — that is, to have all germs excluded 
in the operation, — which is far better than attempting 
to destroy them when once introduced into the wound. 1 

1 Sedgwick, "Principles of Sanitary Science and the Public Health," 
pp. 326, 327. 

140 



DISINFECTANTS, ANTISEPTICS, DEODORANTS 141 

Those substances that destroy foul odors are often 
called disinfectants. This may be true or it may not. 
Some things destroy foul odors, or, in fact, simply cover 
them up without in the least going to the source of the 
trouble, and they are not disinfectants but simply " odor 
killers. " The American Public Health Association's 
committee defines a disinfectant as, " An agent capable 
of destroying the infective power of infectious material." 
This does not, however, represent the popular view of the 
subject. Deodorants, though they may be of great value 
in their place, are not disinfectants or antiseptics. 

Many people are in the habit of relying on the sense of 
smell to prove the presence of injurious as well as dis- 
agreeable substances in the air. The nose is, no doubt, 
an excellent watchman to protect the body, but whether 
we destroy a foul odor or simply overcome it by a more 
pungent one is not for the sense of smell to distinguish, 
for germs that render the air poisonous are not necessarily 
destroyed when no vile odor can be perceived. Because 
a substance is put on the market as a " microbe killer " 
or a " perfect disinfectant," it is not a proof that it is of 
any value, any more than the fact that a patent medicine 
is advertised as a specific for all the ills of the flesh is a 
proof that it will have that effect. 

TESTS FOR DISINFECTION 

These tests may be of three kinds : 1 — 

First. From the practical experience of those engaged 
in sanitary work. Such diseases as smallpox, diphtheria, 
and scarlet fever have in many instances been contracted 
after months, from the use of clothing that has been about 
a patient, or from the occupancy of rooms where he has 
1 Dr. Sternberg, American Public Health Association. 



142 SANITARY AND APPLIED CHEMISTRY 

been sick. Books that have been in the sick room have 
communicated disease months after they were removed 
from the room. If, after an attack of the disease, the 
rooms have been thoroughly disinfected, the disease has 
been completely stamped out in that place. 

Second. Inoculation experiments have been made 
upon animals with infected material, and with the same 
material that had previously been subjected to the action 
of disinfectants. In the former case the disease was 
transmitted, and in the latter it was not, and thus the 
efficiency of the disinfectant was shown. It is known that 
in many infectious diseases the infecting agent is a germ, 
and in these cases the effect of disinfection is to destroy 
the germ. Experiments have been tried upon man with 
disinfected vaccine virus, and with the same virus that 
has not been thus treated, and the vaccination with 
the first was not successful, while that with the latter 
was. In this way the efficiency of a disinfectant was 
shown. 

Third. Culture experiments, as they are called, are 
made directly on the disease germs. Here the germs are 
allowed to propagate in such fluids as extract of beef, or 
bouillon, and thus it is possible to study the life-history 
of these germs outside the body, and to learn what agents 
are efficient in destroying them. 

Some bacteria multiply by " division " and others by 
" spores " also, and the latter are more difficult to destroy, 
because the organism is at that time in what may be called 
a resting stage. Often it is possible to prevent the growth 
and development of germs by the use of antiseptics or dis- 
infectants ; the germs are not destroyed, but the disease 
is arrested. 

" An ideal disinfectant is one which, while capable of 



DISINFECTANTS, ANTISEPTICS, DEODORANTS 143 

destroying the germs of disease, does not injure the bodies 
and material upon which the germs may be found ; it must 
also be penetrating, harmless in handling, inexpensive, 
and reliable. 1 This ideal disinfectant has not yet been 
discovered. " There are, however, some inexpensive 
and common substances which can be used to destroy 
the germs of disease with good effect. Among the sub- 
stances used as disinfectant and antiseptic agents, the 
following may be noted : — 

Sunlight is an excellent disinfectant, if the material can 
be exposed to the direct rays of the sun. It has been shown 
that the bacillus of tuberculosis is killed by direct sunlight, 
and that of typhoid fever also under certain conditions. 
Even diffused light is of value as an adjunct to other 
methods for the destruction of germs, so there is reason in 
the common practice of " airing " bedrooms, and letting 
in all the sunlight possible. 

Dry air is an excellent purifier, especially if accom- 
panied by sunlight, chiefly on account of the large num- 
ber of oxidizing bacteria which are present. It will 
remove moisture and often prevent decomposition in this 
way, for moisture is usually the friend of disease and 
decay. 

Dry earth also allows oxidation and arrests foul odors. 
This fact is utilized in the dry earth closet. 

Charcoal, especially that made from bones, is an excellent 
deodorizer and will remove foul odors quite readily. A 
handful of boneblack sprinkled on a piece of putrefying 
flesh will, after a short time, prevent any foul odors from 
escaping. Wood charcoal acts less effectively in the same 
way, but on account of its porosity absorbs gases very 
quickly. 

1 Price, "Handbook of Sanitation," p. 223. 



144 SANITARY AND APPLIED CHEMISTRY 

Experiment 79. Into a bottle containing 200 cc. of dilute 
hydrogen sulfid water, which has the characteristic odor, put 
about 30 grams of boneblack and shake for some time. Filter, 
and, if the conditions have been carefully observed, the filtrate 
will have no odor of hydrogen sulfid gas, as it will have been 
absorbed by the animal charcoal. 

Quicklime is also used for purposes of disinfection. On 
account of its cheapness, " milk of lime," Ca(OH) 2 , is 
recommended, especially in camp sanitation, for destroy- 
ing foul organic matter. Some physicians regard it as 
efficient as chlorid of lime. 

A variety of substances are used to cover up vile odors, 
while they do not pretend to destroy them. The bad 
smells in the house may be overcome by burning sugar, 
cotton cloth, or coffee. The lack of personal cleanliness 
may be made less noticeable by the free use of perfumes, 
but this is a method belonging to an earlier kind of civiliza- 
tion rather than to our own. 

More effective than any of the methods above noticed 
are the following — in the absence of spores : — 

Heat, at a temperature of 302° F. (150° C), may be 
used for disinfecting, and should be continued for at 
least two hours. A higher temperature, continued for 
a shorter time, will also destroy the bacteria. Sometimes 
clothing that would be injured by moist heat may be 
treated in this way. The goods may be heated in an 
oven, but should not be folded or piled close together. 
This method has been used for disinfecting by boards 
of health in large cities, but it is inferior to steam at the 
same temperature, and does not penetrate as well. 

Sulfur dioxid, made by the burning of sulfur, is one 
of the oldest agents used for disinfection. A convenient 
way in which to use this is to put several pounds of sulfur 



DISINFECTANTS, ANTISEPTICS, DEODORANTS 145 

in an iron kettle, and to place that on bricks in a pan of 
water. Then light the sulfur by means of burning coals, 
or alcohol, and close the room very tightly. Five pounds 
is considered a sufficient quantity for a room containing 
1000 cu. ft. of space. Sometimes a solution of sulfur 
dioxid is simply exposed to the air of the room. Ten 
pounds of the liquid would be necessary for 1000 cu. ft. 
of space. Liquid sulfur dioxid, inclosed in strong steel 
cylinders, may be purchased, and is extremely convenient, 
as it is only necessary to slightly open the valve to allow 
the gas to escape. The presence of moisture in the room 
or on the goods greatly assists the operation. The more 
tightly the room is closed, by pasting strips of paper over 
the cracks beside the doors and windows, the better the 
disinfection will be accomplished, and this precaution 
should not be neglected. Clothing and bedding should 
be opened out as much as possible, so as to bring it in 
contact with the sulfur dioxid gas, and the room should 
remain closed at least twenty-four hours. This gas is 
liable to bleach certain colors, so it should not be used 
with colored fabrics. Sulfur dioxid is, after all, only a 
surface disinfectant, and is said to be effective only 
against a limited number of pathogenic bacteria. 

Carbolic acid, Phenol, C 6 H 5 OH, is an agent that has often 
been overrated, on account of its penetrating odor, and be- 
cause a small quantity will overcome most other odors. 
This acid of a strength of 1 to 15,000 will prevent decom- 
position, but 1 to 1000 will be needed to destroy spores. 1 
" While effective, in weak and in saturated aqueous solu- 
tions against many of the pathogenic bacteria, carbolic 
acid is not suited to the purpose of general disinfection." 2 

1 Price, "Handbook of Sanitation," p. 252. 
2 Harrington, "Practical Hygiene.' ' 
L 



146 SANITARY AND APPLIED CHEMISTRY 

It is an excellent substance to use for washing floors, walls, 
etc., and for disinfecting soiled clothing and discharges, 
as its antiseptic power is great. Although not very- 
soluble in water, the solubility can be increased by the 
addition of glycerin. 

The cresols, which are found in commercial carbolic 
acid, and are powerful germicides, are constituents of 
many of the disinfecting solutions now on the market, 
and they are believed by some to be superior to pure 
carbolic acid. 

Copper sulfate, CuS0 4 5 H 2 0, or " blue vitriol," of 
about 10% strength, is to be recommended, on account 
of its comparative cheapness, especially as a deodorant. 
It forms a blue solution, with water, and is very soluble 
in that agent. 

Iron sulfate, FeS0 4 7 H 2 0, or the " copperas " of com- 
merce, is very efficient for certain purposes. In the pro- 
portion of 2 lb. to a gallon of water, it may be used with 
great convenience and success to purify sink drains and 
cesspools. It may also be sprinkled in places where there 
are foul odors from the decay of organic matter, and they 
will be completely overcome. 

Zinc chlorid, ZnCl2, is very largely used as a disinfectant 
and a deodorant. As its solution, as well as that of zinc 
sulfate, is colorless, it will not stain the most delicate fab- 
rics, so it can be used on any clothing that is not injured 
by washing. A 5 % or 10 % solution may be used for this 
purpose or for destroying foul odors. 

Potassium permanganate, KMn0 4 , since it is a strong 
oxidizing agent, may be used as a germicide in some cases, 
but is rather expensive. The use of this material in the 
purification of cistern waters has already been suggested 
(p. 84). 



DISINFECTANTS, ANTISEPTICS, DEODORANTS 147 

Hydrogen peroxid, H 2 2 , is now a commercial article, 
and its aqueous solution is sold at a reasonable price. 
There are some cases where this mild disinfectant may be 
applied with success, as it will destroy the bacillus of 
typhoid fever, cholera, and diphtheria quite readily. 

There are, however, more efficient agents in disinfection 
than those that have been mentioned, because under the 
proper conditions they are of sufficient power to destroy 
the spores of disease. 

Fire, it is well known, is effective to wipe out the dis- 
ease germs. Old clothing and bedding should be burned 
rather than to try to disinfect it. The great fire of Lon- 
don, that followed the plague, was no doubt a blessing, 
in that it actually destroyed the last traces of the disease. 
That was more important in those days than it would be 
now, for they did not know the first principles of the 
science of disinfection. 

Steam heat is one of the most valuable physical agents 
for the destruction of germs, as it kills bacteria at once, 
and spores after a short time. It is especially valuable 
for the disinfection of clothing, textile fabrics, carpets, 
etc., as it is very penetrating. Municipal authorities 
are making use of this method of disinfection on a large 
scale with great success. If it seems desirable, the ma- 
terial can be subjected to quite a high temperature by the 
use of superheated steam. In some communities ma- 
chines mounted on wheels are used. A large apparatus 
has been introduced which is so constructed that the 
mattresses, bedding, etc., may be put into a chamber, 
from which the air is exhausted by means of a steam 
jet. Dry steam is then allowed to enter, and a tempera- 
ture of 230° to 240° F. is maintained for 15 min., after which 
the steam exhauster again produces a practical vacuum, 



148 SANITARY AND APPLIED CHEMISTRY 

and finally air is drawn through the chamber, and the 
dried materials may be removed. An apparatus of this 
character is used at the New York Quarantine Station. 

Boiling water is one of the most satisfactory materials to 
use for disinfecting purposes. There are very few germs 
that can withstand a boiling temperature for half an hour. 
A temperature of 70° C. will be sufficient to kill the germs 
of cholera, tuberculosis, diphtheria, etc. Hot water is 
specially applicable to textile fabrics. 

Calcium hypochlorite, CaC^O, chlorid of lime, or 
" bleaching powder/' is a convenient disinfectant to use in 
some cases. The chlorid of lime holds the chlorin in com- 
bination very feebly, so that the smell of chlorin is always 
apparent in a good sample. The fresh sample should 
contain from 30 to 36 % of available chlorin, but if it is 
exposed to the air for a time it loses all its chlorin, so 
it must be kept in a sealed package until used. Calcium 
hypochlorite, the efficient substance in the bleaching 
powder, is soluble in water, but the solution loses its 
strength if not closely corked. It is decomposed when 
brought in contact with organic matter, and very effec- 
tually kills the germs of disease. Experiments with chlorid 
of lime as a disinfectant were begun as early as 1881, by 
Koch. They have been continued by Sternberg, Jaeger, 
Nissen, Klein, Duggan, and others, and all showed the 
very efficient character of this substance as a true germi- 
cide. Chlorid of lime is convenient to sprinkle about 
in the vicinity of bad odors, but the odor of the chlorin 
gas given off is disagreeable and in considerable quantities 
poisonous, and furthermore it has a very destructive 
action on metals, so it must be used with discretion. 

Formaldehyde gas, HCHO, or " formalin/' which is a 
40 % solution of the gas, is one of the recent disinfectants 



DISINFECTANTS, ANTISEPTICS, DEODORANTS 149 

of great merit. It first came into general use in 1892. 
As it is a good germicide, has no injurious effect on fabrics 
and colors, and can be readily applied, it is taking the 
place of sulfur dioxid gas. 

There are several ways of applying the gas : The evapo- 
ration of the solution of formaldehyde by means of heat, 
which may be applied in an ordinary kettle, is a simple 
method of disinfection, and one that has proved highly 
effective. Still another method of generating the gas 
is by pouring formaldehyde over crystals of potassium 
permanganate. An ordinary milk pail, set in a wooden 
bucket, so as to retain the heat generated by the power- 
ful chemical action, is all the apparatus needed. In a 
sealed room, 3| ounces of permanganate, over which a 
pint of formaldehyde solution is poured, will be enough 
to thoroughly disinfect 1000 cubic feet of space. Since 
the evolution of gas is very rapid, the operator must leave 
the room immediately. 1 A polymerized formaldehyde, 
known as " paraform," is sold in pastilles, which when 
heated over a lamp give off formaldehyde gas; 2 oz. 
of paraform for 1000 cu. ft. of space, with an exposure 
of 12 hr., is recommended. A large number of lamps 
have been devised for vaporizing the liquid formalin or 
the paraform. The objects to be disinfected may be 
sprinkled with formalin, and inclosed in a tight box, so 
that they may be subjected to the vapor for several hours. 
Another method is to wet sheets with the solution and 
hang them in the room, which is tightly closed. Still 
another method, which may be used on a large scale, 
is to vaporize the formaldehyde gas in a retort outside 
the room, and force it through an opening into the tightly 
closed space. 

1 Rohe and Robin, " A Text Book of Hygiene," pp. 455, 456. 



150 SANITARY AND APPLIED CHEMISTRY 

Mercuric chlorid, HgCl 2 , or " corrosive sublimate/ ' 
which stands probably at the head of all substances used 
as disinfectants and antiseptics, is a deadly poison. In 
solutions of 1 : 15,000 it stops decomposition, and a 1 : 2000 
solution will kill most bacteria in two hours. If of 
1 : 500 strength, it will act very quickly on bacteria and 
spores. It was said by Koch to exercise a restraining 
influence on the development of the spores of anthrax 
bacillus, even when present in the proportion of 1 : 300,000, 
but recent experiments show that its germicidal power was 
overrated. It is of importance to note, however, that 
mercuric chlorid is not very efficient where there is much 
albuminous material, because it so readily forms with the 
latter an insoluble substance. 

If a wound is produced by a rusty nail or by any blunt 
instrument, so that the flesh is lacerated, it should be 
opened as well as possible, and cleansed with warm water 
and then filled completely with a solution of corrosive 
sublimate (1 to 1000), or a solution of carbolic acid of 5 % 
strength should be injected to destroy any dangerous bac- 
teria that may be present. 

Dr. Sternberg recommends the following as a convenient 
solution of corrosive sublimate for general use : — 

Mercury bichlorid 1 oz. 

Copper sulfate 1 lb. 

Water 1 gal. 

The advantage of this solution is that we not only mix 
with the chlorid of mercury a valuable disinfectant, but 
the solution is colored blue, and so it is less liable to be 
used accidentally. It should be marked " Poison.'' 

A disinfectant may be standardized and its relative 
antiseptic power determined by comparing its germ- 



DISINFECTANTS, ANTISEPTICS, DEODORANTS 151 

destroying power with that of a solution of carbolic acid of 
known strength and antiseptic value. Many of the so- 
called microbe killers on the market are shown to be al- 
most worthless when measured by a standard of this 
kind. 



CHAPTER XI 
POISONS AND THEIR ANTIDOTES 

Since many of the substances just discussed are poisons, 
and there are many others which are liable to be taken 
into the system by accident or otherwise, it is of impor- 
tance to have enough knowledge in regard to them so that 
emergency treatment may be applied, but a physician 
should be immediately called. 

GENERAL INSTRUCTIONS FOR TREATMENT 1 

There are some general directions that should be fol- 
lowed in any case of suspected poisoning. If the patient 
vomits, this action should be promoted by giving him 
copious draughts of warm water ; if he is inclined to sleep, 
keep him awake ; if he is faint, he should lie down and take 
stimulants ; and if the extremities are cold, heat should 
be applied. After the stomach is emptied, give bland 
drinks such as starch, oatmeal, gruel, etc., with warm water. 
If an emetic is to be given, use a tablespoonful of ground 
mustard or of common salt in a tumblerful of lukewarm 
water. Other substances that may be used as an emetic 
are 30 grains of zinc sulfate, 30 grains of powdered ipecac, 
or 5 to 10 grains of copper sulfate. 

The opportunities for accidentally taking a poison are 

1 Pharmaceutical Era, N.Y. 
152 



POISONS AND THEIR ANTIDOTES 153 

greatly increased with the use of insecticides about the 
house or farm and the common use of disinfectants. A 
common cause of poisoning is due to the careless habit 
of taking medicine out of an unlabeled bottle, a very dan- 
gerous procedure, or taking medicine from a bottle in 
the dark. Many of the drugs about the house, while 
perfectly harmless for external use, are liable to produce 
fatal results if taken internally. 

A poison is a substance which, taken into the system 
and entering the circulation, may produce serious symp- 
toms, or even death. 

Poisons may be taken in small quantities repeatedly, 
as, for instance, with the food, and this is liable to produce 
chronic poisoning. They may also be taken in larger 
quantities so as to produce severe and dangerous symp- 
toms, and we call this acute poisoning. It is common to 
distinguish between first those substances which, by their 
corrosive action, destroy the lining membranes of the 
alimentary canal, and second the true poisons, which af- 
fect the system after they have been absorbed and have 
entered the circulation. 

To the corrosive class belong the alkalies, potash, soda, 
and ammonia, and the mineral acids, sulfuric, hydrochloric, 
and nitric. The symptoms of these poisons are an al- 
kaline or acid taste in the mouth, followed by severe pain 
in the stomach. 

The treatment, which must be as expeditious as pos- 
sible, in the case of an alkali is to neutralize it immedi- 
ately by administering some vegetable acid, as vinegar, 
or lemon juice in large quantities, and to protect the in- 
terior lining of the stomach by giving sweet oil. 

In the case where acids have been taken, these must 
quickly be neutralized, best by milk of lime, limewater, 



154 SANITARY AND APPLIED CHEMISTRY 

or calcined magnesia. It is not considered very safe 
to administer an emetic in severe cases or to use a stomach 
pump, lest the stomach be ruptured. 

METALLIC POISONS 

The salts of a few of the metals are extremely poisonous, 
and as salts of some of these metals are used in medicine, 
in the arts, as in paints and pigments, as well as for in- 
secticides, there is considerable opportunity for them 
to become mixed with the food. 

These metals are copper, zinc, lead, and mercury, 
and compounds of arsenic and antimony. The symptoms 
are severe pain in the stomach, usually with violent 
vomiting, and later pain in the bowels. When the pres- 
ence of any of these is suspected, an emetic of a table- 
spoonful of ground mustard in water should be given 
immediately to empty the stomach. 

The salts of copper are blue or green and have a strong 
astringent taste. There is no good antidote for the salts 
of copper. We must depend on getting it out of the 
stomach as quickly as possible by an emetic, unless, in- 
deed, as is often the case with copper sulfate, it acts itself 
as an emetic. 

The salts of zinc are white and astringent and might 
readily be mistaken for some harmless substance like 
magnesium sulfate or " salts/ ' There seems to be no 
satisfactory antidote for zinc. It fortunately happens, 
however, that salts of zinc when taken into the stomach 
usually produce violent vomiting. This can be aided 
by taking warm water and ground mustard. The whites 
of half a dozen eggs mixed with water may also be given. 

Salts of lead are white unless they are compounds of 
some other metal like chromium; the lead chromate, 



POISONS AND THEIR ANTIDOTES 155 

which has been used for coloring candy, is of a brilliant 
orange color. Since lead salts are precipitated by sul- 
fates, an excellent antidote for lead poisoning is mag- 
nesium or sodium sulfate. This should be followed by 
an emetic. 

Mercury salts are also white. The most common 
of these are mercurous chloride (Hg 2 Cl 2 ), commonly 
known as " calomel/ ' which is not considered a poison, 
and corrosive sublimate (HgCl 2 ), which is extremely 
poisonous. Since the latter is a common disinfectant, 
there is every opportunity to take it by mistake. Corro- 
sive sublimate forms an insoluble precipitate with albumen, 
so the method of treatment is to administer the whites 
of several raw eggs. If these are not at hand, a flour 
paste, on account of the gluten which it contains, may be 
used. An emetic should then be given, or in some cases 
the stomach pump may be used. 

The substance known as arsenic is arsenic oxid (AS2O3). 
It is a white, tasteless powder. Arsenic is often used 
as the basis of rat poisons and of vermin powders 
and fly killers. It is also the active ingredient of such 
insecticides as Paris green and London purple. " Rough 
on Rats " contains arsenic diluted with the white mineral 
substance barium sulfate and colored with lampblack. 
Arsenic is, therefore, a common poison. The symptoms 
of arsenical poisoning are severe pains in the stomach and 
bowels, and usually violent vomiting, accompanied by 
great thirst. The method of treatment is to give an 
emetic and afterwards freshly precipitated ferric hydrate 
(Fe 2 (OH) 6 ) in tablespoonful doses. This may be pre- 
pared by the precipitation of ferric chlorid by ammonium 
hydrate, or by magnesium oxid. 

Antimony salts are also poisonous. The most common 



156 SANITARY AND APPLIED CHEMISTRY 

of these is tartar emetic, which is sometimes taken by 
mistaking the label tartar emetic for cream of tartar. 
The symptoms of poisoning are similar to those of ar- 
senic poisoning. Unfortunately there is no good antidote 
for antimony and we must depend on removing it from 
the stomach by means of an emetic. 

One of the common poisons is oxalic acid. This is a 
white crystalline solid, having the appearance of magne- 
sium sulfate, for which it has often been mistaken. This 
acid and its salts are much used in the arts, as in laundry 
work and in dyeing and calico printing. The symptoms 
of poisoning are an acid taste in the mouth, pain in the 
throat and stomach, and persistent vomiting. If no anti- 
dote is given, it may be fatal in less than twenty-four 
hours. The antidote is lime in some form, as calcium 
carbonate, whiting, or precipitated chalk. An emetic may 
be given. 

A very quick acting poison is hydrocyanic or Prussic 
acid. The common compound of this found on the market 
is potassium cyanid (KCN). This substance, as well 
as the acid, has an odor resembling that of peach pits, 
or bitter almonds. It finds abundant use in the arts, 
as in the separation of gold and silver from their ores, and 
in silver plating. The acid itself is a very volatile liquid, 
a few drops of which will produce almost instant death. 
The symptoms appear usually within five minutes after 
the poison is taken. The patient suffers from great weak- 
ness, vertigo, and a feeling of impending suffocation, as 
the muscles of respiration are particularly affected. 
With a large dose the patient almost immediately loses 
consciousness. The best method of treatment is to induce 
respiration as in a case of drowning. Aromatic spirits 
of ammonia may be used to stimulate breathing. The 



POISONS AND THEIR ANTIDOTES 157 

stomach may be washed out with a dilute solution of po- 
tassium permanganate or hydrogen peroxid. There is 
usually very little time in which to treat the patient. 

Phosphorus poisoning is not as frequently met with at 
present as when phosphorus was more extensively used 
in matches. In most of the " safety matches " the phos- 
phorus paste is on the box and not on the matches. As 
phosphorus is an ingredient of common rat poisons and 
vermin killers, it might be taken accidentally. 

The symptoms of acute phosphorus poisoning, which do 
not appear until several hours after the poison is taken, 
are pain in the stomach, severe headache, followed by 
nausea and vomiting. Sometimes the odor of phosphorus 
is noticed in the breath. 

The best method of treatment is to give an emetic 
and wash out the stomach with a dilute solution of po- 
tassium permanganate. The antidote generally recom- 
mended, after the poison has been removed, is a dose of 
from fifteen to thirty grains of old oil of turpentine. 

Another class of poisons quite distinct from those 
already mentioned is the alkaloids. These are the active 
principles of various plants and, although very numerous, 
only a few of the more common ones need be considered 
here. 

Morphine is one of the alkaloids obtained from the 
juice of the seed capsule of the poppy. This dried juice 
is known as opium. Like all alkaloids its salts have a 
bitter taste, and very small quantities produce a marked 
effect on the system. Morphine is a constituent of lau- 
danum, paregoric, and a very large number of sedatives, 
including the soothing sirups used for infants. 

The symptoms, which usually appear within half an 
hour after the poison is taken, are first, a period of excite- 



158 SANITAKY AND APPLIED CHEMISTRY 

ment, which is soon followed by an intense desire to sleep. 
In the third stage the patient lies motionless, and an exam- 
ination of the eyes will show that the pupils are con- 
tracted to the size of pinheads, and are insensible to the 
action of light. 

In a case of morphine poisoning the physician will 
try to remove any poison that remains in the stomach 
by washing it out with a solution of potassium perman- 
ganate (5 grains in a teacup of water) with a stomach 
tube or syphon. Unfortunately it frequently happens 
that an emetic will not work. The next thing is to keep 
the patient moving, if it is at all possible, by walking 
him in the open air. Strong coffee may be administered 
in certain stages of the treatment. 

Strychnin is a very active poison found in the Nux 
vomica bean. This poison is so often used to poison rats, 
moles, squirrels, dogs, and other animals that it is quite 
readily obtained. 

The symptoms, which appear within a few minutes 
after the poison is taken, are an intensely bitter taste, 
followed very soon by twitching of the muscles and later 
by what are known as tetanic convulsions. During these 
spasms the muscles are rigidly contracted, and if relief 
is not afforded the spasms occur more and more frequently. 
An attempt to drink or a slight jar is liable to produce a 
spasm. 

Unabsorbed poison should be removed from the stomach 
best by the hypodermic administration of apomorphin, 
or mustard in warm water may be given. A decoction 
of tannin with sodium bicarbonate is sometimes used to 
wash out the stomach. Chloroform may be cautiously 
administered by inhalation, or chloral hydrate by the 
mouth. 



POISONS AND THEIR ANTIDOTES 159 

The plant popularly called monkshood or wolfsbane 
contains an extremely poisonous alkaloid known as 
aconite. The root looks something like horseradish 
and has sometimes been mistaken for it. Very small 
quantities of the tincture of the root or of the active prin- 
ciple will cause death. The symptoms, which appear 
within a few minutes after the poison is taken, are a pecul- 
iar tingling sensation in the mouth, followed by nausea, 
and frequently a strangling sensation. An emetic should 
be immediately given; artificial respiration should be 
maintained ; stimulants should be administered. 

Chloroform, if taken into the stomach, or when acci- 
dentally inhaled, acts as a poison. It should be removed 
from the stomach without delay, and artificial respiration 
should be given, accompanied by the inhalation of pure 
oxygen. If chloral hydrate is taken in excess above a 
medicinal dose, the patient should be treated as in a case 
of chloroform poisoning. 

Poisoning by carbolic acid is very common, as it is readily 
obtained. It acts as a corrosive on the mouth and ali- 
mentary tract, and produces a burning sensation, and 
sometimes vomiting. In severe cases the patient is 
liable to become unconscious after a short time. The 
stomach should be washed out, and saccharated lime 
and alkaline sulfates or magnesia mixed with olive oil 
should be administered. The best antidote is whisky 
or brandy. 

Wood alcohol, wood spirit or methyl alcohol (CH 3 HO), 
is liable to be taken accidentally for grain alcohol 
(C2H5OH). It produces very serious and often fatal 
effects. In case the patient survives, he is liable to be 
permanently blind. Wood alcohol should be removed 
from the stomach by an emetic as quickly as possible. 



160 SANITARY AND APPLIED CHEMISTRY 

An effort should be made to aid in the elimination of 
the alcohol by free sweating and by the administration 
of large quantities of water in which sodium bicarbonate 
(baking soda) is dissolved. 

Ptomaine poisoning is often reported after eating food 
consisting of meat, chicken, fish, sausage, ice cream, or 
cheese. The usual symptoms are nausea and very severe 
pain in the stomach and bowels. Ptomaines are liable 
to be produced by the partial spoiling of foods, as when 
they are stored in damp, dark, dirty places, or in filthy 
containers. Contrary to common opinion, fruits and 
vegetables do not contain ptomaines. An emetic should 
be given and a physician called immediately. 

There are numerous poisonous gases, but the one of 
special importance that should be here noted is carbon 
monoxid (CO). This is the most poisonous constituent 
of coal gas and water gas, and is also produced by the 
imperfect combustion of coal. As the carbon monoxid 
gas when pure has no odor, it is quite liable to be breathed 
accidentally. 

The symptoms are a severe headache, vertigo, and 
muscular weakness, followed by general insensibility. The 
patient should be removed to the open air and treated 
by artificial respiration. The body should be kept warm, 
and ammonia may be cautiously inhaled. 

It is important to remember that no gases except air 
can be breathed in safety. Other gases replace the oxygen 
of the air and the patient dies from suffocation or lack of 
oxygen. This refers to carbon dioxid and such vapors 
as that of gasoline, benzol, carbon tetrachlorid, and similar 
organic substances. 



[PART II 

CHEMISTRY OF FOOD 



CHAPTER XII 

USE OF FOODS 

In the consideration of so broad a subject as food, there 
is difficulty at the outset in giving it a satisfactory defini- 
tion. The growth and repair of the body, as well as the 
potential energy by virtue of which the body is able to do 
actual work, need to be taken into account. Food has 
been defined as, " Anything which, when taken into the 
body, is capable either of repairing its waste or of furnish- 
ing it with material from which to produce heat or nervous 
and muscular work." l It is important to distinguish 
between food and medicine, and to notice that the latter 
may revive some vital action but will not supply the 
material which sustains that action. There are, however, 
many articles of diet, such as tea and coffee, and the food 
accessories, such as spices and condiments, which, although 
they do not strictly come within the above definition, are 
often useful to stimulate the appetite or to make the food 
more agreeable. 

It is by no means essential that a single food should con- 
tain all the nutrients needed by the body, and in fact it is 

1 Hutchison, "Food and Dietetics," p. 1. 
M 161 



162 SANITARY AND APPLIED CHEMISTRY 

desirable that there should be a variety of food to stimu- 
late the appetite and vary the character of the work which 
the organs of digestion are called upon to perform. Food 
may contain substances which must be broken up or 
decomposed by the body before it is of value, or it may 
contain substances which can immediately be taken into 
the circulation and utilized. 

Some food is of use because it furnishes nearly all the 
nutritious substances needed by the body, while other 
foods furnish some special material in an economical 
or agreeable form. Some act readily in sustaining the 
body, or are easily digested ; others are economical and 
offer a maximum amount of nourishment at a minimum 
cost. 

Not only does food sustain the body, but there is a 
provision of nature that animals should derive great 
pleasure and satisfaction from eating, and this pleasure 
is due to both the sense of smell and that of taste ; it is 
difficult to consider the function of one without that of 
the other. 

Since these senses have not been cultivated as highly as 
the others, there is much room for further development ; 
but there are some trades, such as that of the tea taster, 
the wine sampler, and the perfumer, where they are culti- 
vated and utilized. The student of physiology finds it 
difficult to classify the sense of taste and smell, but it is 
possible to test the relative delicacy of these senses for 
various substances in different individuals. Some experi- 
ments l made by the author for the delicacy of the sense 
of taste, with a number of persons of both sexes, showed 
that it was possible to detect — 

1 Science, Vol. XI, p. 145. 



USE OF FOODS 



163 





By Males 


By Females 




(1 part in) 


(1 part in) 


1 Bitter substance (quinine) .... 


392,000 


456,000 


2 Acid substance (sulfuric acid) . . . 


2,080 


3,280 


3 Salt substance (sodium chlorid) . . 


2,240 


1,980 


4 Sweet substance (cane sugar) . . 


199 


204 


5 Alkali substance (baking soda) . . 


98 


126 



This showed that the sense of taste for bitter substances 
was far more delicate than for other classes, and that, 
except in the case of salt, the females could detect smaller 
quantities than the males. A separate set of tests made 
upon the pupils in a large Indian school * showed the 
same order of delicacy. 

The knowledge that man has obtained as to which foods 
are wholesome and which are poisonous is largely the result 
of experience, and this experience was transmitted and 
grew from one generation to the next. Much is due, 
then, to our ancestors, who have had the courage to ex- 
plore in the realm of untasted food. Even now, fatal mis- 
takes in the selection of food are sometimes made, and 
children must in every generation be warned against 
brilliantly colored berries. 

In the early ages the variety of food was not as great as 
now, for the people not only had less skill in preparing 
and less experience in selecting food, but they were obliged 
to depend on the chase, or to use only that food which was 
obtained in the immediate vicinity of their dwellings. 
They were not able to draw on all climates as we do, nor 
could they preserve the fruits of one season to consume in 
another. Grain was stored, fruits were dried, and meats 



1 Kans. Univ. Quarterly, Vol. II, p. 95. 



164 SANITARY AND APPLIED CHEMISTRY 

were salted or dried, but beyond this little was done to 
preserve food. 

A mixed diet, then, may be considered as evidence of 
advancing civilisation. The palate becomes surfeited 
with too much of one kind of food, and so a change is 
welcome to stimulate the appetite. A monotonous diet 
is often a matter of necessity, but as soon as man has the 
opportunity to indulge in a mixed diet he is not slow to 
take advantage of it. ^Yith increased civilization the 
diet becomes more mixed in character, and on this account 
it does not interfere with the health to move from one 
locality or climate to another. 

There is no doubt that man, as well as the lower animals, 
is benefited by a variety in food. It has been stated that 
" digestion experiments made with one kind of food 
material do not give on the whole as valuable results as 
those in which two or more food materials are used. In 
other words, it appears that with a mixed diet the same 
person will digest a larger proportion of nutriment than 
with a diet composed of a single food material." It is, 
of course, admitted that a mixed diet may present greater 
temptations to overindulgence in food. 

It stands to reason that as some foods are too rich in 
proteins and others contain too large a proportion of carbo- 
hydrates, we should mix these in the proper quantities. 
This we do when we eat " bread and cheese," potatoes 
and beef, or rice, eggs, and milk in puddings. 

As the system adapts itself to a certain kind of food and 
the stomach secretes gastric juice sufficient in kind and 
quantity for that food, it is not advisable after being ac- 
customed to one kind of diet for a long time to change too 
suddenly to one that is entirely different, for indigestion 
may result. 



FV 



USE OF FOODS 165 

The food selected should be suited to the habits, age, 
and employment of a person. A sedentary man will not 
thrive on a diet that is too stimulating, nor one engaged 
in active manual labor upon starchy foods alone. The 
food that is readily digested by an adult will not be at all 
adapted to the use of a young child. 

There seems to be an instinctive selection of particular 
classes of foods for special climates — the Eskimo eats 
large quantities of whale blubber or fats; the Congo 
natives live mostly upon the plantain; the Polynesians 
subsist almost wholly on breadfruit. Even in the tem- 
perate zone we find that less meat is eaten in warm 
weather. 

COOKING FOODS 

Food, in order to be agreeable and wholesome, is usually 
cooked. This is necessary, — 

First, to improve its appearance and to make it more 
agreeable to the eye and thus more appetizing. 

Second, because warm food is often more agreeable than 
cold. 

Third, to improve the flavor and develop the odor, 
particularly in the case of meats. 

Fourth, in order to destroy any parasites or micro- 
organisms that may be contained in the food. 

Fifth, to bring about certain chemical changes in the 
food, and thus better adapt it to digestion. 

Sixth, to soften the material so that it may more readily 
be acted upon by the digestive fluids. 

When proteins, such as those of meat, are acted upon 
by heat, even if the temperature is not above 170° F., 
they are coagulated and made more solid, but they are not 
so tough, and the bundles of fibers may more easily be 



166 SANITARY AND APPLIED CHEMISTRY 

torn apart. When starchy food, as grains or potatoes, 
is cooked, the granules swell up, the outer cellulose en- 
velope bursts, and thus after mastication the digestive 
ferments have an opportunity to come more intimately 
in contact with the starch. According to Sykes, moist 
heat, even below 185° F., causes most starch grains to burst, 
so that the starch is said to be gelatinized. 1 



CHARACTER OF FOODS 

Food must be of such a character that it will build up 
the tissue of the body and supply it with energy for doing 
work. Incidentally the heat of the body is kept up by 
cell action, or, as one author puts it, " is a by-product " 
of functional activity. It is not necessary nor advisable, 
however, that all the food taken into the body should be 
positively nutritious. It will be a long time before the 
dreams of those who propose that we carry concentrated, 
or perhaps " synthetic," foods for several days' rations in 
the vest pocket will be realized. Not only would such 
food soon become positively insipid and disagreeable, 
but there is an absolute necessity for a certain amount of 
inert matter to distend the walls of the alimentary canal 
and distribute the nutrient material so that it may the 
more readily be absorbed. 



FOOD MATERIAL NEEDED 

Too large an amount of indigestible material in the food 
is, on the other hand, not satisfactory, for not only does it 
require of the different organs an undue amount of work 

1 Hutchison, "Food and Dietetics," p. 378. 



USE OF FOODS 167 

in handling it, but the indigestible material may act as a 
positive irritant in the stomach and bowels. Too coarsely 
ground cereals sometimes overstimulate and irritate the 
mucous surfaces and thus become a source of impaired 
digestion. Not only should the food contain the nourish- 
ing material,, but this should be of such a character that 
it is exactly adapted to the wants of the body. 

In order to find out what the human body needs for its 
sustenance we may notice either the composition of the 
body, or we may study milk, which is the food provided by 
nature to nourish the young. The body contains the 
following chemical elements : oxygen, carbon, hydrogen, 
nitrogen, phosphorus, sulfur, chlorin, fluorin, silicon, cal- 
cium, potassium, sodium, magnesium, iron, manganese, 
and copper — sixteen in all. 

The fact that these elements are found, however, means 
very little, if we have no information as to how they are 
combined, what proximate substances or compounds they 
form, for these elements might be combined to form innu- 
merable substances. 

According to a recent authority, 1 the body of a man 
weighing 154 pounds is made up of the following com- 
pounds, in approximately the quantities noted in the 
table : — 

1 A. H. Church, "Food," p. 5. 



168 



SANITARY AND APPLIED CHEMISTRY 





Pounds 


Ounces 


Water, found in all the tissues 


109 




Albumen, myosin, etc., found in muscular 






flesh, chyle, lymph, and blood .... 


16 


8.0 


Calcium phosphate, found in tissues and 






liquids, but chiefly in the bones and teeth 


8 


12.0 


Fat, distributed through the body . . . 


4 


8.0 


Ossein, or collagen, found in the bones and 






connective tissues 


4 


7.8 


Creatin, etc., in the skin, nails, and hair . . 


4 


2.0 


Cartilagin, found in the cartilages . . . 


1 


8.0 


Haemoglobin, a substance containing iron, 






found in the blood 


1 


8.0 


Calcium carbonate, in the bones .... 


1 


0.8 


Neurin with lecithin, cerebrin, and similar 






compounds, found in the brain, nerves, etc. 





13.0 


Calcium fluorid, found in the bones and teeth 





7.4 


Magnesium phosphate, chiefly in bones and 






teeth 





7.0 


Sodium chlorid, throughout the body . . 





7.0 


Cholesterin, inosite, and glycogen, which are 






found in brain, muscle, and liver . . . 





3.0 


Sodium sulfate, phosphate, carbonate, etc., 






found in all liquids and tissues .... 





2.2 


Potassium sulfate, phosphate, and chlorid, 






found in all liquids and tissues .... 





1.7 


Silica, found in hair, skin, and bone . . . 





0.1 



Besides the above there are other complex compounds 
which occur in small quantities, but which are none the 
less of importance. Each of the proximate principles is 
made up of two, three, four, or possibly more, elements, 
and the compounds thus formed are some of them very 
complex in their structure. 

CLASSIFICATION OF FOODS 

No classification of food is very satisfactory, for al- 
though we may adopt the classification of Liebig and divide 



USE OF FOODS 169 

the foods into the carbonaceous, or those which furnish 
heat, and nitrogenous, or those whose function it is to 
build up the body and furnish muscular energy, we are 
met at the outset by the fact that a large number of foods 
partially fulfill both functions. The cells of the body may 
draw their supply of energy from proteins, albuminoids, 
carbohydrates, or fats ; but material for the manufacture 
and repair of tissues must come from the proteins. Heat 
is produced as a result of cell action. 1 

PROXIMATE SUBSTANCES 

The proximate substances that go to make up foods 
include (1) water, (2) fat, (3) carbohydrates, (4) protein 
and related nitrogenous bodies, (5) organic acids, and (6) 
the mineral salts. Water, although absolutely essential 
as a constituent of the food material, need not be con- 
sidered in the light of a nutrient. The fats which occur 
both in vegetable and animal foods are glycerids of the 
fatty and other acids. They contain only carbon, 
oxygen, and hydrogen. The oxygen is not present in 
sufficient quantity so that with the hydrogen it would 
form water. Fats are more fully discussed under Soap, 
p. 130, also on p. 57 and in Chapter XX. 

1 Hutchison, "Food and Dietetics," p. 3. 



CHAPTER XIII 

CELLULOSE, STARCH, DEXTRIN, ETC 

CARBOHYDRATE FOODS 

The carbohydrates include, with a few exceptions, only 
those compounds of carbon, hydrogen, and oxygen in 
which the hydrogen and oxygen are in the proportion to 
form water; that is, two parts of hydrogen to one of 
oxygen. Here are included the cereals and most standard 
foods, with the exception of the fats and those that are 
nitrogenous in character. These foods may be divided 
into : — 

1. The cellulose group (C 6 Hi O5)„, including cellulose, 
starch, inulin, dextrins, gum, etc. 

2. The cane-sugar group (C12H22O11), including cane 
sugar, milk sugar, maltose, etc. 

3. The glucose group (C 6 Hi 2 6 ), including dextrose, 
levulose, grape sugar, starch sugar, and galactose. 

In addition to the above, inosite, C 6 Hi 2 6 ,H20, which 
occurs in muscular tissues, and pectose, the jelly-pro- 
ducing substance of fruits and vegetables, should accord- 
ing to some authors be classified as carbohydrates. 

The ordinary analysis of a foodstuff includes a deter- 
mination of the amount of water, fat, nitrogenous matter, 
carbohydrates, and ash. A study of thses analyses is of 
value in the comparison of different foods. 

170 



CELLULOSE, STABCH, DEXTBIN, ETC. 171 

CELLULOSE 

Cellulose (C 6 Hi O 5 ) n is the main product of vegetable 
life, and forms the principal part of wood, cotton, 
paper, etc. In fact, cotton fiber, linen rags, and 
" washed " filter paper are nearly pure cellulose. It is 
insoluble in most chemical reagents, but may be dissolved 
in cuprammonia, and from the solution the cellulose may 
be precipitated as a gelatinous mass which is similar to 
aluminum hydroxid in appearance and dries to a hard 
mass. 

When cotton or paper is treated with a mixture of nitric 
and sulfuric acids, a substance called nitrocellulose is 
formed. One variety of this substance is guncotton. 
When the nitrocellulose is dissolved in ether, it yields 
collodion. Another product known as celluloid is made 
by dissolving certain varieties of nitrocellulose in ether 
and camphor, and afterwards evaporating off the sol- 
vent. There are some special properties of cellulose, 
which are illustrated in the experiments which follow 
this section. 

Although some of the lower animals, as the rodents, can 
digest cellulose and make it available for nutrition, the 
stomach of man has this power only to a limited extent. 
According to Atwater, some of the cellulose of the food is 
absorbed, but much of it passes through the system un- 
changed and is of value only as it helps distend the alimen- 
tary canal. Whatever digestion takes place in the in- 
testines is due to the action of certain microorganisms, by 
which fatty acids are produced, which upon absorption 
yield nutriment. Herbivorous animals eat food that 
contains large amounts of cellulose associated with smaller 
quantities of starch, fat, and nitrogenous substances. 



172 SANITARY AND APPLIED CHEMISTRY 

Experiment 80. To 3 volumes of water add 1 volume con- 
centrated sulfuric acid and cool the mixture. Pour this into 
an evaporating dish, and immerse in it strips of unsized paper, 
and allow them to soak for 10 to 15 seconds. Wash thoroughly, 
first with water, then with dilute ammonia solution, and again 
with water. Dry the parchment paper or amyloid thus ob- 
tained, and notice its peculiar properties. Although it has 
undergone a physical change, it still has the composition of 
paper. Unsized cloth may be treated in the same way. 

Experiment 81. Another sample of unsized paper is treated 
with strong sulfuric acid, and allowed to stand for 5 minutes. 
It dissolves into a pulpy mass, which is then washed thoroughly, 
and tested with tincture of iodin. If a purple color is produced, 
it is an indication that the cellulose has been changed to dextrin. 

Experiment 82. To show the action of alkalies on cellu- 
lose, treat a piece of cotton cloth for 20 minutes with a solu- 
tion of sodium hydroxid of a specific gravity of 1.25. Wash 
and dry, and notice the change in the structure of the fiber. 
This is practically the process used to make " mercerized " 
goods. In this process the linear contraction is about 25%, 
and the increase of strength is 50%. See also p. 115. 

* Experiment 83. Make cuprammonia (Schweitzer's re- 
agent), Cu(NH 3 ) 4 S04, as follows: Add to a cold solution of 
copper sulfate, a cold solution of sodium hydroxid, filter, 
wash, and dissolve in concentrated ammonium hydroxid and 
add a little dilute sulfuric acid. Schweitzer's reagent should 
be freshly prepared, and should be capable of immediately 
dissolving cotton or fine grades of filter paper. It may be 
used to dissolve cellulose from pectose, in working with the 
microscope. 

* Experiment 84. Dissolve cotton or filter paper in Schweit- 
zer's reagent, and add to the solution an excess of hydrochloric 
acid. This will precipitate the cellulose, which may be washed 
on a filter so that its properties can be examined. See also 
p. 115. 



CELLULOSE, STARCH, DEXTRIN, ETC. 



173 



STARCH (C 6 H 10 O 5 ) n 

The starches are regarded as the most important of the 
foods of this group ; indeed, they form the principal part 
of most vegetable foods. Starch is stored up in seeds, 
roots, fruits, and vegetables, and is adapted for food pur- 
poses; and is utilized by man and the lower animals. 
As the bee stores honey for future use, so the plants store 
starch for the use of the germinating seed, and man takes 
advantage of both kingdoms of nature. The carbohy- 
drates circulate through the plant in the form of sugar, but 
they are stored up in the form of starch, and this store 
can be drawn upon by the plant in time of need. 

Sources of Starch. — The most important source of 
starch is the cereals. The amount of starch contained in 
some grains is as follows : — 





Pee Cent 


Wheat flour . . 


. . 75.6 


Graham flour . 


. . 71.8 


Corn meal . . 


. . 71.0 


Oatmeal . . . 


. . 68.1 


Rye flour . . 


. . . 78.7 



Per Cent 

Rice 79.4 

Buckwheat flour . . . 77.6 

Barley 62.0 

Sorghum seed .... 64.6 

MiUet 60.0 



Various roots, tubers, and stems are also sources of 
starch, as follows : x — 



Per Cent Per Cent 

18.0 Artichokes (gum and 

15.3 inulin) 10.2 

15.0 Sweet cassava (tapioca) 30.98 

2.5 Arrowroot (Maranta 

3.5 arundinaceoe) . . . 22.93 

3.0 Onions (pectose, etc.) . 4.8 

2.4 Radishes (carbo- 
hydrates) .... 4.6 

1 For complete composition, see "Foods," by A. H. Church. 



Potato . . . 
Yam .... 

Sweet potato . 
Carrots (pectose) 
Parsnips . . . 
Turnips (pectose) 
Beets (pectose) 



174 SANITARY AND APPLIED CHEMISTRY 

Some less familiar sources of starch are the Sago palm, 
and the roots of the Bitter cassava (tapioca), Salep (or- 
chids), Tous les mois {Carina edulis), and Celeriac. 

The leguminous plants also furnish starch, thus : — 

Per Cent Per Cent 

Beans 57.4 Peanuts 117 

Peas . 51.0 Soy beans 12.5 

Lentils 56.1 

There is some starch in all fruits, but those mentioned 
are of special value on account of the amount which they 
contain : — 

Per Cent Per Cent 

Bananas 22.0 Breadfruit 14.0 

Plantain . . . . 15 to 20 

Some nuts contain considerable starch, thus : — 

Per Cent Per Cent 

Acorns 43.35 Horse chestnuts . . . 68.25 

Chestnuts 42.10 

Of the above, the most important commercial sources of 
starch are wheat, corn, rice, potatoes, acorns, and chest- 
nuts. Special varieties of starch are also put on the market 
under the names of tapioca, arrowroot, and sago. The 
other starch-bearing vegetable products, as well as those 
specially noted, are used in some countries as food. 

WHEAT 

The examination of the wheat grains by the microscope 
shows that upon the outside there are bran cells ; next to 
these are cells of a thin cuticle ; within these are the gluten 
cells, and finally, nearer the center of the grain, are the 



CELLULOSE, STARCH, DEXTRIN, ETC. 175 

starch cells. If a longitudinal section be made of a 
wheat grain, and it is examined by a microscope of low 
power, it will be found to be made up of the " germ," 
which is near one end, the " kernel," and the "bran," 
or outer envelope. 1 

Wheat is a typical bread-making cereal. Its proteins 
differ from those of other cereals, and are composed 
chiefly of a globulin, an albumin, a proteose, and the two 
bodies, gliadin and glutenin. 2 The two latter form the 
gluten, and give the characteristic properties to wheat 
flour. The products of wheat are used as human food 
in many forms. There are nearly a hundred different 
grades of food materials made from wheat by the patent- 
roller process of milling. 3 

Wheat sown in the fall is called soft or winter wheat, 
and that sown in the spring is hard or spring wheat. 
The kernels of winter wheat are usually larger than the 
spring variety. Spring wheat usually contains more 
gluten than winter wheat. 

In comparing the milling and the food value of wheat, 
it should be remembered that this depends largely on the 
amount of nitrogenous matter present. A high percentage 
of proteins is not always a sure indication of the milling 
value of the wheat. It is the gluten content of the flour 
on which the bread-making qualities chiefly depend. The 
percentage of dry gluten is considered the safest index to 
use in the comparison of different samples of flour. 

A comparison of the analysis of different samples of 
wheat is of interest : 4 — 

1 For full description, see Jago, "The Science and Art of Bread Mak- 
ing," p. 265. 

2 Osborn and Voorhees, Am. Chem. Jour., Vol. XV, p. 392. 

3 Bui. 13, Pt. 9, U. S. Dept. Agric, Div. Chem. 
* Wiley, Bui. 45, U. S. Dept. Agric, Div. Chem. 



176 



SANITAEY AND APPLIED CHEMISTRY 





Moisture 


Albumi- 
noids 


Ether 
Ext. 


Crude 
Fiber 


Ash 


Carbo- 
hydrates 


Domestic . . . 


10.62 


12.23 


1.77 


2.36 


1.82 


71.18 


Foreign .... 


11.47 


12.08 


1.78 


2.28' 


1.73 


70.66 


World's Fair, 1893 


10.85 


12.20 


1.74 


2.35 


1.81 


71.09 


Mean, given by- 














Jenkins & Winton 














Spring . . . 


10.40 


12.50 


2.20 


1.80 


1.90 


71.20 


Winter . . . 


10.50 


11.80 


2.10 


1.80 


1.80 


72.00 


Mean, by Konig 














Miscellaneous . 


13.37 


12.51 


1.70 


2.56 


1.79 


68.01 


Spring Wheat . 


13.80 


14.95 


1.56 


— 


2.19 


67.93 


Russian, Spring 


12.56 


17.65 


1.58 


— 


1.66 


65.74 



There are, however, some special varieties of wheat, 
including a Russian wheat, that contain more protein. 
Twenty-four analyses of this variety show an average of 
21.56 % of nitrogenous substances. 1 Durum wheat is 
one of the hard, glassy varieties especially adapted to the 
making of macaroni. The ash of wheat contains about 
30 % of potash, 3 % of lime, 12 % of magnesia, and 47 % 
of phosphoric anhydrid, besides the other constituents 
that are usually found in the ash of plants. From this 
it is easy to understand that a large amount of mineral 
matter is taken from the soil by a crop of wheat. 



WHEAT FLOUR 



Wanklyn states that wheat flour has the following com- 
position : — 

Per Cent Per Cent 

Water 16.5 Starch, etc 69.6 

Fat 1.2 Ash 0.7 

Gluten, etc 12.0 

1 Blyth, "Foods, Their Composition and Analysis," p. 146. 



CELLULOSE, STARCH, DEXTRIN, ETC. 



177 



As wheat flour was formerly made, it was crushed 
between millstones, forming a rather coarse product ; 
this was bolted, and gave fine flour, middlings, and bran. 

At the present time, by the roller process, in which the 
grain is crushed and sifted repeatedly, a large number of 
grades of flour may be produced. 

The highest grade of flour produced is known as Patent 
flour, while the lower grades are often known as Family, 
Bakers', and Red Dog flour. The following analyses show 
the percentage of the different products produced from the 
grain, and the grades obtained by different millers : — 





Minnesota * 


Akkansas 2 


Patent flour 


57.82 

11.28 

6.77 

17.64 

3.79 

2.70 


17.65 


Straight flour 


50.35 


Bakers' flour 

Low-grade flour 

Bran 


2.32 
24.10 


Shorts 


1.10 


Screenings, waste, etc 


4.48 




100.00 


100.00 



The commercial value of a flour depends on its color, 
texture, and the quantity of gluten which it contains. 
The character of this gluten also differs under different 
conditions of climate and soil. Bakers prefer a flour with 
a high percentage of tenacious gluten, which permits the 
production of a loaf of bread containing a maximum 
amount of water. This water may be as high as 40 %. 3 
In large bakeries the best results are obtained by mixing 
different grades of flour. 

1 Snyder, Minn. Agric. Exp. Sta., Bui. 90. 

2 Teller, Ark. Agric. Exp. Sta., Buls. 42, 53. 

s U. S. Dept. Agric, Div. Chem., Bui. 13, Pt. 9. 

N 



178 



SANITARY AND APPLIED CHEMISTRY 



ANALYSIS OF DIFFERENT KINDS OF FLOUR 

Some of the constituents of different kinds of flour 
are as follows : * — 





Moisture 


Nitrogen 
N X 6.25 
Proteins 


Dry 

Gluten 


Ether 
Extract 


Nitrogen- 
free 
Extract 


Patent wheat 












flour . . . 


12.77 


10.55 


9.99 


1.02 


74.76 


Common market 












wheat flour 


12.28 


10.18 


9.21 


1.30 


75.63 


Bakers' and 












family flour . 


11.69 


12.28 


13.07 


1.30 


73.87 


Indian-corn flour 


12.57 


7.13 


— 


1.33 


78.36 


Rye flour . . . 


11.41 


13.56 


— 


1.97 


73.37 


Barley flour . . 


10.92 


7.50 


— 


.89 


80.50 


Buckwheat flour 


11.89 


8.75 


— 


1.58 


75.41 



For a comparison of the different grades of wheat flour, 
the following table, which gives the results of work done 
at the University of Minnesota, 2 is of interest : — 



Milling 


Water 


Protein 


Fat 


Carbo- 


Ash 


Phosphoric 


Product 


NX 5.7 


hydrates 


Acid 


First patent flour 


10.55 


11.08 


1.15 


76.85 


0.37 


0.15 per ct. 


Second pat. flour . 


10.49 


11.14 


1.20 


76.75 


.42 


.17 


Straight or 














Standard patent 


10.54 


11.99 


1.61 


75.36 


.50 


.20 


First clear- 














grade flour . . 


10.13 


13.74 


2.20 


73.13 


.80 


.34 


Second clear- 














grade flour . . 


10.08 


15.03 


3.77 


69.37 


1.75 


.56 


"Red Dog" flour 


9.17 


18.98 


7.00 


61.37 


3.48 


— 


Shorts .... 


8.73 


14.87 


6.37 


65.47 


4.56 


— 


Bran .... 


9.99 


14.02 


4.39 


65.54 


6.06 


2.20 


Entire-wheat 














flour .... 


10.81 


12.26 


2.24 


73.67 


1.02 


.54 


Graham flour . . 


8.61 


12.65 


2.44 


74.58 


1.72 


.71 


Wheat ground in 














laboratory . . 


8.50 


12.65 


2.36 


74.69 


1.80 


.75 


Gluten flour . . 


8.57 


16.36 


3.15 


70.63 


1.29 





1 Bui. 13, Pt. 9, U. S. Dept. Agric, Bu. Chem. 

2 Snyder, U. S. Dept. Agric, O. Exp. Sta., Bui. 101. 



CELLULOSE, STARCH, DEXTRIN, ETC. 179 

From the figures in the table it will be seen that there is 
a gradual decrease in the water content from the first 
patent to the " red dog " grade of flour, and there is a 
noticeable increase in the ash from the higher to the lower 
grades. The determination of ash has been taken advan- 
tage of to determine the grade of a particular sample of 
flour. 

There is but little difference in chemical composition be- 
tween the first and second grades of patent flour. The 
" standard " patent flour contains about 12 per cent of 
protein, while the wheat from which it was made contains 
12.65 %. The second clear and " red dog " samples are 
characterized by a high per cent of protein, fat, and ash. 
Judging by their proximate composition only, these latter 
flours might appear to have a higher nutritive value than 
the higher grades ; but, when judged by the character of 
the bread made from them, they must be assigned a 
much lower value (see p. 175). 

The wheat product of the United States for 1915 was 
over 1,011,505,000 bu. 

CORN {MBA MAYS) 

Corn, though coming originally from America, has been 
largely cultivated in some other countries. It grows well 
in temperate and warm climates all over the world. The 
grains keep well, and may be parched, or ground into meal. 
There are a large number of varieties of corn, a special 
variety being adapted to each special climate. By care- 
ful selection C. G. Hopkins 1 has increased the protein 
of a variety of corn from 10.92 % to 14.26 %. 

Some of the preparations of corn are hominy, samp, 

1 Rep. Ills. Agric. Exp. Sta. Bull. 100 (1905). 



180 SANITARY AND APPLIED CHEMISTRY 

corn meal, cracked corn, cerealin, and a large number of 
corn starches. The examination of the analyses made by 
the Department of Agriculture x shows that corn has the 
following composition : — 

Per Cent Per Cent 

Moisture . . . . . 10.04 Crude fiber .... 2.09 

Albuminoids .... 10.39 Ash 1.55 

Ether extract (mostly Carbohydrates . . . 70.69 

fats) 5.20 

CORN AS FOOD 

Corn is especially rich in fats, although deficient 
in nitrogenous matters and mineral salts. It is a very 
fattening food, both for man and the lower animals, and is 
well adapted to serve as food for those who do hard man- 
ual labor. As it was first introduced into Europe as 
food for lower animals, it has been somewhat difficult 
to overcome the prejudice of the people against it, al- 
though the United States government has sent a com- 
mission to Europe to demonstrate to the people the value 
of corn as a food for man. Corn meal is quite digestible, 
though slightly laxative. Cornstarch is frequently used 
as a substitute for other starches in food for invalids. 
In this country, both yellow corn meal, made from hard 
corn of the Northern States, and white corn meal, made 
from the white corn of the West, are in use. 

Referring to the relative nutritive properties of wheat 
and maize, Wiley 2 says : " There is a widespread opinion 
that the products of Indian corn are less digestible and 
less nutritious than those from wheat. This opinion, 
it appears, has no justification, either from the chemical 

1 Bui. 45, Dept. Agric, Div, Chem., p. 25. 

2 U. S. Dept. Agric, Div. Chem., Bui. 13, Pt. 9, p. 1290. 



CELLULOSE, STARCH, DEXTRIN, ETC. 181 

composition of the two bodies, or from recorded digestive 
or nutritive experiments. In round numbers, corn con- 
tains twice as much fat or oil as wheat, three times as 
much as rye, twice as much as barley, and two thirds as 
much as hulled oats. Indian corn has nearly the same 
content of nitrogenous matter as the other cereals, with 
the exception of oats." 

The largest corn crop of the United States, that of 
1912, amounted to 3,124,746,000 bu. ; that of 1915 was 
3,055,000,000. 

OATS 

Oats are grown in northern regions throughout the 
civilized world. The composition of oatmeal is as 
follows : l — 

Per Cent Per Cent 

Water 12.92 Dextrin and Gum . . 2.04 

Nitrogenous matter . 11.73 Starch 51.17 

Fats 6.04 Fiber 10.83 

Sugar 2.22 Ash 3.05 

Oatmeal contains considerable fat, protein, and mineral 
salts. The nitrogenous substance is composed of 
" gliadin " and plant casein. The gliadin has a much 
higher percentage of sulfur than the gliadin of wheat. 
Von Bibra states that oatmeal contains from 1.24 to 
1.52 % of albumen. It has proved an excellent food- 
stuff, though, on account of the quality of the gluten, it 
is not adapted to use for making bread. Within the last 
forty years it has come into extensive use in the United 
States as a breakfast food. It is stated that the so-called 
Scotch groats are prepared by removing the outer husks 

iBlyth, "Foods, Their Composition and Analysis," p. 170. 



182 SANITARY AND APPLIED CHEMISTRY 

and leaving the grain almost whole, and then this is 
ground between millstones. True Scotch groats are 
heated over perforated iron plates and slightly parched 
before being ground. In most cases where oatmeal can 
be digested, it forms a very valuable food, but it requires 
long cooking (from one to two hours) and considerable 
skill in preparation to make it wholesome. On this 
account, although it has been used so extensively for many 
years, recently other foods have to some extent been 
substituted for it. Possibly we have not appreciated the 
fact that it is a very hearty food and especially suitable 
for those who live an outdoor life. The oat crop of the 
United States for 1915 was 1,540,000,000 bushels. 

RYE 

This cereal grows best in northern countries, where it is 
sown in the fall and protected by the covering of snow in 
the winter. It is the favorite food of northern Europe, 
where it is made into " black bread.' ' It was formerly 
quite extensively used as food in the extreme northern 
part of the United States. The grain is also much used 
for malting purposes. It makes a better bread when mixed 
with wheat flour in the proportion of two of wheat to one 
of rye. This grain is more liable than other cereals to be 
affected by the fungus known as ergot. Grain that is 
modified in this way is unwholesome and may be poisonous. 
On account of its composition, rye dough is very sticky, 
and of a dark color. The composition of American rye 
is as follows : — 

Moisture Albuminoids Ether Extract Crude Fiber Ash Carbohydrates 

8.6 11.32 1.94 1.46 2.09 74.52 

The rye crop of the United States for 1915 was 49,200,- 
000 bushels. 



CELLULOSE, STARCH, DEXTRIN, ETC 183 

BARLEY 

This grain was originally a native of western Asia, 
and is well adapted to high northern latitudes. Both 
barley meal and " pearl barley/ 7 that is, the grain de- 
prived of the outer coating by attrition, are used as food. 
By far the largest part of the barley that is grown is used 
for making malt (see Chapter XXV). Barley flour 
does not .yield a light bread, but may be mixed with wheat 
flour for this purpose. The following is the composition 
of the grain : — 

Moisture Albuminoids Ether Extract Crude Fiber Ash Carbohydrates 

11.31 10.61 2.09 4.07 2.44 69.47 

237,000,000 bushels of barley were produced in the 
United States in 1915. 

MILLET 

This cereal is raised for stock food in the United States, 
but is a staple diet for man in central Africa, southern 
Europe, and eastern Asia. In protein value it is between 
wheat and rice. Although the bread made from millet 
is nutritious, it soon crumbles and becomes dark in 
color. 

RICE 

This cereal is a native of India and is grown in the East, 
in southern Europe, and in the southern United States, 
where it was introduced in 1644. For its successful culti- 
vation an abundance of water, so that the fields can be 
irrigated, and a high temperature are required. Although 
rice is deficient in albuminoids, fat, and mineral matter, 



184 



SANITARY AND APPLIED CHEMISTRY 



it is estimated that it is the main food of a third of 
the human race. 1 To prepare the grain for the market 
it is separated from the hulls, and is usually polished by- 
passing between leather rollers which remove the outer 
layer. This process of "polishing," however, removes 
much valuable nutrient material. The grains are also 
ground into flour or may be used for making starch. Rice 
has the following composition, according to Konig : 2 — 





Moisture 


Albumi- 
noids 


Ether 
Extract 


Crude 
Fiber 


Ash 


Carbo- 
hydrates 


Hulled . . 
Polished . 


12.58 
12.52 


6.73 

7.52 


1.88 

.84 


1.53 

.48 


.82 
.64 


76.46 
78.00 



This grain is exceedingly digestible when cooked, espe- 
cially by steaming, so that the individual grains are 
softened and swollen. It cannot be made into raised 
bread unless mixed with wheat or rye flour, as it is deficient 
in gluten. 

It is evident from the composition of rice that it is not 
fit to use as an exclusive food, but should be eaten with 
butter, eggs, and milk, as in puddings, or with meat, fish, 
peas, or beans, to supply the necessary food ingredients. 
When rice is cooked in a soup or with meat, the mineral 
salts, which at best are not very abundant, are fully 
utilized in the food. 

PRODUCTION OF RICE 

For the year 1913 there was produced in the United 
States 715,111,000 pounds of rice, and this was about 

1 " Foods, Their Origin, Composition and Manufacture," Tibbies. 

2 Bui. 45, U. S. Dept. Agric, Div. Chem., p. 34. 



CELLULOSE, STARCH, DEXTRIN, ETC. 185 

2-^-0 of the total production of the world. 1 We import 
annually not less than 200,000,000 pounds from foreign 
countries. 

POTATOES 

The potato, Solanum tuberosum, is closely allied botani- 
cally to several interesting plants, including the tomato, 
tobacco, henbane, and capsicum. Although a native of 
Chili and Peru, it was probably carried to Spain early in 
the sixteenth century, and introduced into Virginia from 
Florida by the Spanish explorers, and into Great Britain 
from Virginia in 1565 by Sir John Hawkins. The potato 
was recommended by the Royal Society of London in 1663 
for introduction into Ireland as a safeguard against 
famine. It is a question whether its introduction there 
has not aggravated the famine tendency, since the peas- 
ants learned to depend almost entirely on potatoes, and 
this crop sometimes failed from disease. It was not 
cultivated in New England till the eighteenth century, 
when it was introduced from Ireland ; and now this 
" much traveled " tuber is one of the most important 
articles of food. 

Potatoes grow well and are a staple crop in the New 
England States, New York, Michigan, Canada, and 
throughout the Middle West. Even where the season 
from frost to frost is quite short a good crop may be raised. 
359,000,000 bushels were grown in the United States in 
1915, 2 and the world's crop is over 5,500,000,000 bushels. 

The following analysis is given by Church : — 

1 "Rice, Cleaning and Polishing," Stuart, U. S. Dept. of Agric. 

2 Monthly Crop Report, Sept. 1916. 



186 SANITARY AND APPLIED CHEMISTRY 

Per Cent Per Gent 

Water 75.0 Dextrin and pectose . . 2.0 

Albuminoids .... 1.2 Fat 3 

Extractives, as solanin 

and organic acids . . 1.5 Cellulose 1.0 

Starch 18.0 Mineral matter . . . 1.0 

This shows that 93 % of the potato is water and starch, 
and that, as in the case of rice, the amount of fat, albumi- 
noid, and mineral matter is very small. But with even 
this small mount of nitrogenous substance, experiments 
have proved that only 49 % of this is protein, the remainder 
being ammonium compounds and salts, which are of no 
value as nutrients. The grains of potato starch are very 
large as compared with those of the cereals. Commercial 
starch is readily obtained from this tuber, and this is a 
convenient method for utilizing small and immature 
potatoes. The starch is also very readily attacked by 
ferments, and so potatoes are often used as an ingredient 
of home-made yeast. 

A cross section of the potato shows that it is made up of 
a rind, which constitutes 2\ % ; a fibrovascular layer, 8| % ; 
and the flesh, 80% ; and an analysis has shown that the 
fibrovascular layer is much richer in mineral matter and 
proteins than the body of the potato, so by the ordinary 
method of peeling much valuable nutrient material is 
lost. It is estimated that 20 % of the actual weight of 
the potato is usually thrown away as refuse. The mineral 
matter is rich in potash salts, and when the potato is 
peeled before boiling, much of this and of the valuable 
protein matter is dissolved and wasted. If potatoes 
are peeled, there is less loss of nutrient material if they 
are plunged immediately into boiling water and boiled 
rapidly. Potatoes may also be steamed or baked without 
appreciable loss. 



CELLULOSE, STARCH, DEXTRIN, ETC. 187 

Potatoes are evidently not suited for use as the staple 
article of diet, but are extremely useful as food when eaten 
with butter, milk, eggs, meat, and fish, and this is indeed 
the ordinary method of using them. They are very valua- 
ble to prevent scurvy, and usually form an indispensable 
addition to the diet upon shipboard, where salt meats 
are necessarily used. During the Great War in Europe 
potato flour, or dried and ground potato meal, were 
added to that made from cereals in making bread. 

SWEET POTATOES 

The sweet potato belongs to the convolvulus family, and 
is probably a native of tropical America, though it grows 
well in temperate climates. The yam is a different 
plant, although there is a resemblance between the 
tubers of this plant and the sweet potato. Sweet potatoes 
have the following composition : x — 

Per Cent Per Cent 

Water 75.0 Pectose 9 

Albuminoids, etc. . . 1.5 Fat . , 4 

Starch 15.0 Cellulose 1.8 

Sugar 1.7 Mineral matter . . . 1.5 

Dextrin and gum . . . 2.2 

CASSAVA (TAPIOCA) 

Tapioca is a starch product made from the roots of 
several plants of the manioc family, that grow in parts 
of South America and in other tropical regions. One of 
these, the Manihot utilissima, or bitter cassava, yields a 
milky juice, which in the preparation of the tapioca is 
mixed with the starch, and this contains considerable of 

1 Church, "Food," p. 107. 



188 SANITARY AND APPLIED CHEMISTRY 

the poison known as prussic acid, HCN. In the prepara- 
tion of the tapioca, this juice is washed away from the 
grated root and the pulp is heated on hot plates, to drive off 
the last of the prussic acid ; this treatment also ruptures 
most of the starch grains. 1 Tapioca is considered one of 
the most useful foods for invalids. A tapioca flour is made 
by grinding the dried pulp, and this forms the chief food 
of the natives in many tropical countries. A so-called 
" pearl tapioca " is often made from potato starch. 

ARROWROOT 

The commercial arrowroot is made from the rhizome 
of the Maranta arundinacea, a plant growing in the West 
Indies. The roots are washed, reduced to a pulp and 
mixed with water, strained, and from the milky water 
the starch settles out. The granules of the starch thus 
prepared are among the largest used in commerce. The 
product when cooked is one of the most valuable foods 
for the diet of invalids. In making and packing the so- 
called Bermuda arrowroot, great care is observed to keep 
it from contamination. 

SAGO 

This form of starch is made from the pith of the sago 
palm, which grows in Sumatra, Java, Borneo, and the 
West Indies. The starch is washed out of the pith after 
the tree has been felled, and is converted into " pearl " 
sago by granulation. A palm tree frequently yields 500 
pounds of sago. 

1 Bui. 44, U. S. Dept. Agric, Div. Chem. 



CELLULOSE, STARCH, DEXTRIN, ETC. 189 

OTHER STARCHY FOODS 

Chestnuts contain 15 % of sugar and from 25 to 40 % of 
starch. Although used for making bread by the French, 
Spanish, and Italians, it is not a very digestible form of 
starch. 

Some of the other starches of interest are salep, which 
is made in Smyrna, from a species of orchid, and is used 
in Turkey and the East as food ; Tous les Mois, manufac- 
tured in the West Indies from the tubers of Carina edulis; 
and a starch prepared in Japan from the bulbs of several 
varieties of lily. 

All the more expensive starches are liable to adulteration 
with cheap starches, such as that of wheat, corn, or rice, 
and these adulterations can only be detected by the use of 
the microscope. 

LEGUMES 

Under the general name of " pulse" may be classified such 
important foods as peas, beans, soy beans, lentils, etc., 
which come from the leguminous plants. It is said that 
peas came originally from the country around the Black 
Sea. Beans were introduced into Europe from India, and 
lentils were grown from the earliest time in southern 
Europe and the country to the east and south of the 
Mediterranean Sea. The soy bean is an important article 
of food in China and Japan, and supplements very well 
the rice diet in these countries. 

These foods are characterized by containing not only 
large quantities of starch, but proteins as well, so they 
may be considered as furnishing, at the same time, both 
kinds of nourishment needed by the body. On this 
account, the legumes are often classified with the nitrog- 



190 



SANITARY AND APPLIED CHEMISTRY 



enous foods. Plants of this family have a special provi- 
sion for getting enough nitrogen for their growth, in the 
little nodules on the roots, which consist of masses in- 
closing bacteria, which have the power of fixing the free 
nitrogen of the air so it can be utilized by the growing 
plant. Peas and beans also contain some sulfur and phos- 
phorus, in combination with the nitrogenous body known 
as legumin, or vegetable casein.- 

Legumin of the unripe peas appears to be more soluble 
and more readily digested than that from the dried seeds. 
On the whole, the leguminous foods are not readily digested 
in the stomach, but are quite thoroughly absorbed in the 
intestines. 1 If, however, the food is not ground to a state 
of very fine subdivision, there is quite a loss of proteins 
in the process of digestion. 

The following analyses are given by Hutchison : — 







Water 


Proteins 


Carbo- 
hydrates 


Fat 


Cellulose 


Mineral 
Matter 


Green peas . 
Dried peas . 
Beans . 

Lentils . . 


78.1 
13.0 
11.7 
11.7 


4.0 
21.0 
23.0 
23.2 


16.0 

55.4 
55.8 
58.4 


0.5 
1.8 
2.3 
2.0 


0.5 
6.0 
4.0 
2.0 


0.9 
2.6 
3.2 
2.7 



While the leguminous foods are excellent diet, yet they 
should be supplemented by the food containing starch and 
fat, and so we use beans and rice, or, more commonly, 
baked beans and fat pork. In the latter case, the oil or 
melted fat permeates the mass in cooking, and flavors 
the beans, and, at the same time, furnishes a more digest- 
ible diet than if the same amount of fat was used for fry- 
ing. 

1 Hutchison, "Food and Dietetics," p. 223. 



CELLULOSE, STARCH, DEXTRIN, ETC. 191 

Green peas and green beans, as well as " string beans/ ' 
do not furnish a very highly nutritive diet, as they con- 
tain from 80 to 90 % of water, but, on account of the 
ready solubility of the proteins and their agreeable flavor, 
they form a valuable food product. 

On account of the cheapness of this form of protein food, 
a pea sausage (Erbswurst) has been introduced as a part 
of the rations in the German army. It is a cooked food, 
made of pea meal mixed with fat pork and salt, so pre- 
pared that it will not readily spoil. 1 In cases where it is 
necessary to economize in the cost of food, this can be 
readily attained by the use of relatively large quantities 
of peas, beans, and lentils, for they contain large amounts 
of nutrients at a comparatively low cost. 

* Experiment 85. To prepare legumin, treat pea flour with 
successive quantities of cold water, made slightly alkaline. In 
this solution precipitate the legumin with acetic acid. To 
purify, dissolve the precipitate in weak potassium hydroxid 
solution and reprecipitate with acetic acid. The pure alkaline 
solution should give a violet color, with copper sulfate solution. 2 

BANANAS 

The banana, although a variety of the plantain family, 
is smaller and more delicate in flavor than the common 
plantain. Although the banana grows as far north as 
Florida, yet the climate best adapted to its cultivation is 
that of Cuba, Jamaica, the Congo region in Africa, and 
especially Central America. 

The tree grows to a height of from 12 to 40 feet. When 
the stalk of the tree is cut down, new stalks shoot up from 
the roots. The tree is propagated on a new plantation, 

1 Thompson, "Practical Dietetics," p. 163. 

2 Blyth, "Foods, Their Composition and Analysis," p. 181. 



192 



SANITARY AND APPLIED CHEMISTRY 



not by seeds, but by cutting off roots from old plants, and 
planting in rows, very much like the hills of corn. The 
banana comes to maturity from the root in from ten to 
twelve months. Each bunch that is produced will con- 
tain from 150 to 180 bananas. 

The banana-growing industry has increased enormously 
in the past thirty years, and at the same time the cost of 
the fruit has decreased. Bananas which a few years ago 
cost 10 cents apiece can now be bought at from 10 to 15 
cents a dozen. The fruit is shipped to the United States 
in fast steamers that are capable of carrying 40,000 
bunches per trip. In 1914, 41,000,000 bunches were 
shipped into the United States, or an estimated consump- 
tion of forty bananas per capita per year. 

Bananas are peculiar in combining the sweet qualities 
of a fruit with the nourishing qualities of a vegetable. On 
account of the presence of so much nutriment, and be- 
cause bananas grow so luxuriantly, it is stated that a given 
area of ground will support a greater population if planted 
to bananas than if planted with wheat. 

The analysis of bananas compared with some other 
starchy foods is as follows : — 





Ripe 
Bananas x 


Potatoes 2 


Banana Flour 

from 

Ripe Fruit 3 


Wheat 
Flour 3 


Moisture . . 


73.10 


78.3 


13.0 


13.8 


Nitrogenous 










substances . 


1.87 


2.2 


4.0 


7.9 


Fat ... . 


.63 


.1 


.5 


1.4 


N.-free extract 


23.05 


18.4 






Carbohydrates 






80.0 


76.4 


Cellulose . . 


.29 








Ash ... . 


1.06 


1.0 


2.5 


.5 



1 Konig, "Chem. d. M. Nah. u. Genuss.," p. 1120. 

2 Rep. Ct. Agric. Exp. Sta. 3 Hutchison, p. 249. 



CELLULOSE, STARCH, DEXTRIN, ETC. 193 

From this analysis it is evident that bananas are rich in 
sugar or starch and contain a fair quantity of proteins. 

Some persons find bananas difficult of digestion, but this 
is no doubt due to the fact that they are often picked so 
green that they are irregularly ripened. The partially 
ripened fruit is composed chiefly of starch, and this 
should be cooked before it is eaten by invalids. As the 
fruit ripens, this starch changes to a mucilaginous sub- 
stance, and then to dextrin and glucose. 

A banana flour is made by carefully drying selected 
fruit, and is said to be easily digested and extremely nutri- 
tious. This is about the only fruit flour that can be 
readily made, and so it has been used with success as a part 
of the diet of patients suffering from gastric irritability 
and similar diseases. A plantain meal is made by drying 
the pulp of the unripe fruit. 

GENERAL METHOD FOR MAKING STARCH 

In the United States starch is made especially from corn 
(maize), wheat, and potatoes; in Europe, potatoes, corn, 
and rice are used ; and in the West Indies starch is made 
from arrowroot or the sago palm. 

Several processes are used for the manufacture of starch. 
In making cornstarch by the Durgen system a continuous 
stream of water at 140° F. is allowed to flow over the corn 
for three days in order to soften it. It is then ground in 
water and the milky liquid is run into nearly horizontal 
revolving sieves, or square shaking sieves. The starch 
passes through the bolting cloth, and the refuse, which con- 
sists of the cellular tissue, is retained. The refuse is after- 
wards pressed and used for cattle food. The water, hold- 
ing the starch in suspension, is allowed to stand in wooden 



194 SANITARY AND APPLIED CHEMISTRY 

vats until the starch settles out, when the water is finally 
drawn off. In order to purify the starch and remove the 
gluten, the crude starch is agitated with a solution of caus- 
tic soda, allowed to settle, and the clear liquid drawn off. 
Next the starch is washed and run into a deep vat, and the 
highest of a series of plugs is removed from the side to allow 
the starchy liquid to run out. A little later a lower plug 
is removed, and so on until the vat is nearly empty ; then 
a fresh lot of starch water is run in. The products from 
the different lots of starchy water drawn off are of different 
grades and used for different purposes. After again 
sifting through bolting cloth, the starch solution is run 
into wooden settling boxes, and when sufficiently compact 
is cut into blocks and dried on an absorbent surface of 
plaster of Paris in a current of warm air. It is important 
that the temperature of the moist starch be not raised 
above 60° C. 

In another process the milky liquid is run upon an in- 
clined settling floor, and made to run slowly back and forth 
toward the lower end of the room. The starch is deposited 
and the clear water run off at the lower end. Sometimes 
alkali is not used, but the germ of the corn is mechanically 
removed before the starchy part of the corn is ground. 

In making wheat starch the softened grain is sometimes 
ground and then allowed to ferment for 14 days in large 
tanks at 20° C, with frequent stirring. By the fermenta- 
tion which takes place the gluten is attacked and the starch 
grains are set free. The impure liquid is drawn off and the 
starchy mixture is poured through revolving sieves or made 
to pass through the meshes of hempen sacks. The subse- 
quent operations are like those above described. 

By another process wheat flour is mixed with water, 
and the dough is washed repeatedly in bags under a jet 



CELLULOSE, STARCH, DEXTRIN, ETC. 195 

of water. Starch is obtained from the water by running 
it into settling tanks, and the gluten which remains in the 
bags may be utilized for making macaroni. 

Experiment 86. Mix a handful of flour with water, and 
place the dough in a cloth bag, hold under a stream of 
running water, kneading constantly with the hands. The 
starch will be carried away with the water and the gluten will 
remain in the bag. Dry the contents of the bag, and examine 
its structure. 

The insoluble proteins of wheat obtained by kneading a 
dough of wheat flour in a stream of water consist of about 
75 % of true gluten (gliadin and glutenin), together with 
small percentages of non-gluten proteins, mineral matter, 
fat, starch, fiber, and other non-nitrogenous matter. 1 

Experiment 87. As the value of a flour for baking bread 
depends on the amount of gluten present, the following method 
has been used to compare the gluten-content of flours. 2 Place 
10 g. of flour, wet with an equal weight of water, in a porcelain 
dish, and work into a ball with a spatula, taking care that 
none adheres to the dish. Allow the ball to stand for an hour, 
then knead it with the hand in a stream of cold water until the 
starch and soluble matter are removed. Allow the ball of gluten 
to remain in cold water for an hour, then roll into a compact 
ball with the hands, place in a watch glass, and weigh ; this is 
moist gluten. Dry for 24 hours on a water bath and again 
weigh, and then record the weight as that of dry gluten. 

SUBSTANCES RELATED TO STARCH 

Dextrin (C 6 Hi O 5 ) is a'substance that suggests gum in its 
properties, and indeed it is put upon the market under the 
name of British gum. Several varieties of dextrin exist, 
and it is evident from a study of their composition that 

1 Norton, J. Am. Ch. Soc, 1906. 

2 Wiley, " Agric. Analysis," 2d edition, Vol. Ill, p. 530. 



196 SANITARY AND APPLIED CHEMISTRY 

they may result from the breaking down of the starch 
molecule, by means of dilute acids or ferments. 

Commercial dextrin is made either by heating starch or 
flour to a temperature of 210-280° C, or by moistening the 
starch with a mixture of dilute nitric and hydrochloric acid, 
slowly drying the paste, and heating it to a temperature 
between 110° and 159° C. 

Dextrin obtained by either of these processes is a white or 
yellowish powder. As it is mostly of the variety known as 
erythrodextrin, its aqueous solution gives a brown color 
with iodin. It is slightly soluble in dilute alcohol, but 
insoluble in 60 % alcohol. The brown crust on the outside 
of a loaf of bread is composed mostly of dextrin. Dextrin 
is used on the back of postage stamps to make them adhe- 
sive. 

The Gums are colloidal bodies occurring in the juices of 
plants. They either dissolve or swell up when brought in 
contact with cold water. Some of the more important 
gums are : Gum Arabic and Gum Tragacanth. Their 
food value has only been imperfectly studied. 

Inulin (C 6 Hio0 6 ) is a starchlike substance found in chic- 
ory, potatoes, artichokes, elecampane, dahlias, and dande- 
lion roots. It is a white powder, readily soluble in boiling 
water, and converted into levulose by boiling with water 
or acids. 

PHYSICAL PROPERTIES OF STARCH 

Starch is really made up of little grains, those of different 
plants being of different size and shape, and showing con- 
centric markings. This indicates that the grains are built 
up of different layers ; that is, a layer of true starch and 
then a layer of a kind of cellulose. These grains are not 
soluble in cold water, alcohol, or ether, so they are not 



CELLULOSE, STARCH, DEXTRIN, ETC. 197 

washed away when the plant is broken. If boiling water 
is poured upon the starch, or if starch is heated to from 70° 
to 80° C, the grains burst and the whole forms a gelatinous 
mass, having, when dry, the stiffening properties with 
which we are familiar. In order to thoroughly cook 
starch so that it will be digestible, it should be noted that 
at some time in the process it should be heated as high as 
100° C. Boiled with water for a long time, the starch goes 
into solution, 1 part dissolving in 50 parts of water. In 
the process of cooking starchy foods, the grains are rup- 
tured, and in this condition they are much more easily 
attacked by the digestive fluids. 

As all starches are of practically the same composition, 
the only way of detecting the source of any specimen of 
starch is by the use of the microscope. Although there 
are so many varieties, yet the grains of each differ from the 
others in size or shape, or in their appearance with polarized 
light. The expert can thus detect adulterations and the 
substitution of a cheap starch for an expensive one. For 
illustrations of the different starches, see Leach x (plates) . 

Experiment 88. Place some starch in a test tube with a 
little water and shake moderately, then filter and test the filtrate 
for starch by adding tincture of iodin (see Experiment 93). 
If there is no blue color, how is this accounted for ? 



CHEMICAL PROPERTIES OF STARCH 

When starch is heated to 100° C, it changes gradually to 
soluble starch. At a temperature of 160° to 200° C. it is 
changed to dextrin (C 6 H 10 O 5 )n; from 220° to 280° C. it 
is changed to pyrodextrin, which is soluble in alcohol. Of 

1 Leach, " Food Inspection and Analysis," 3d ed. 



198 SANITARY AND APPLIED CHEMISTRY 

course, if heated still higher, it is decomposed and gives off 
combustible gases. 

Experiment 89. Prepare starch from potatoes by peeling, 
scraping to a pulp, putting in a cloth bag with water, and 
squeezing out the milky juice. Allow this to settle (not over 
24 hr.), pour off the clear liquid, and dry the residue at a tem- 
perature not above 70° C. on a water bath. 

Experiment 90. Make starch from corn meal and from 
acorn meal, by grinding with water in a mortar and treating 
as in Experiment 89. 

Experiment 91. Make an emulsion of green bananas, 
and prepare starch from this, as above. 

Experiment 92. Make starch paste by mixing a few grams 
of one of the specimens of starch prepared above with cold 
water and pouring this into 100 times as much boiling water 
and heating for a short time. 

Experiment 93. Test a small portion of this starch paste, 
after cooling, with a few drops of tincture of iodin. (This 
is made by dissolving iodin in alcohol.) A blue color indicates 
the presence of starch. 

Experiment 94. To make dextrin (C 6 Hi O5) n , heat about 
20 g. of starch very cautiously in a porcelain evaporating dish, 
with constant stirring. The temperature should be between 
210° and 280° C. 

Experiment 95. Another method of making dextrin is to 
moisten about 10 g. of starch with a very little dilute nitric acid, 
dry the paste on a water bath, and finally heat slightly above 
100° C. 

Experiment 96. Dissolve some of the dextrin made above 
in cold water (characteristic test) ; add to this solution an excess 
of alcohol, to precipitate the dextrin. 



CELLULOSE, STARCH, DEXTRIN, ETC. 199 

Experiment 97. Prepare Fehling's solution as follows : — 
(a) Dissolve 34.639 g. of copper sulfate in 500 cc. of water. 
(6) 178 g. of Rochelle salts and 30 g. of sodium hydroxid 

are dissolved in water and diluted to 500 cc. Label 

the solutions a and b. 

Experiment 98. Fettling' s Test for Dextrose. To a dilute 
solution of commercial glucose, contained in a medium-sized 
test tube, add 5 cc. of a and 5 cc. of 6, and boil for a few minutes. 
The formation of a yellowish red, or, in case of an excess of 
dextrose, of a red flocculent precipitate of cuprous oxid, CU2O, 
indicates dextrose. 

Experiment 99. Test a portion of the dextrin made in 
previous experiments, dissolved in water, 

(a) for starch with tincture of iodin, 

(b) for sugar (dextrose) with the Fehling's solution, as 
mentioned above. 



HYDROLYSIS OF STARCH 

By boiling with dilute acids starch is converted into 
dextrin and maltose, and by prolonged boiling into dex- 
trose. This process of taking up the molecule of water is 
known as hydrolysis. (See equation below.) Many 
ferments like the ptyalin of saliva and the pancreatic 
ferment change starch to sugar (C 6 Hi 2 6 , dextrose) . 

Experiment 100. Conversion of Starch to Dextrose. Use 
about 3 g. of the starch made above ; mix with 200 cc. of water 
and 20 cc. dilute HC1. Heat on a water bath in a flask for 2 
hours, or boil for 15 minutes. Cool, neutralize with sodium 
hydroxid, and test a portion of the solution by Fehling's solu- 
tion for dextrose. 

If starch is digested with the diastase of malt, what is 
known as " hydrolysis " takes place and the starch is 



200 SANITARY AND APPLIED CHEMISTRY 

changed to maltose, C12H22O11 + H 2 0, which resembles dex- 
trose. The action of malt upon starch is expressed by the 
equation : — 

3 C6H10O5 + H2O = C6H10O5 + C12H22O1L 

Starch Dextrin Maltose 

Experiment 101. Filter some saliva, and digest this with 
starch paste in a test tube, kept in a water bath at a tempera- 
ture not above 98° F. (36.6° C.) for 15 min. Test half of the 
solution for starch and the other half for maltose by Fehling's 
solution. 

Experiment 102. To show the presence of sulfocyanic acid 
(HCSN) in saliva, evaporate cautiously a few cc. in a small 
porcelain crucible and test with a few drops of dilute ferric 
chlorid (FeCy. The reddish coloration indicates the presence 
of sulfocyanids. 

Experiment 103. Prepare malt extract by digesting coarsely 
pulverized malt for several hours with enough alcohol to cover 
it. Filter and set the solution aside in an evaporating dish. 
When the alcohol has evaporated, dissolve the residue, which 
contains the ferment known as diastase, in water. Make a 
thin starch paste, cool to about 62° C, add a little of the diastase, 
and digest for 15 min. at this temperature. Test a portion of the 
solution for starch. If it is still present, continue the digestion, 
but if it is all converted, test for maltose by Fehling's solution. 

Strong nitric acid in the cold acts upon starch, produc- 
ing several nitroamyloses, collectively known as xyloidin. 
These resemble nitrocellulose (see p. 171). 



CHAPTER XIV 
BREAD 

Whether we consider th6 white bread of the American 
housewife, the black bread of the German peasant, the 
oatmeal " scones " of the Scotch laborer, or the corn 
" pone " of the Southern plantation, each is a valuable 
nutrient and a staple food in its locality. 

Bread consists practically of flour, with the addition of 
a little salt and water, mixed into a paste and baked before 
a fire. The simplest flour is that made by the natives of 
many countries, by grinding, or " braying/' the grain 
betw r een two stones. This was one of the earliest mortars 
used. It is quite probable that the name " bread " comes 
from the word " brayed," referring to this method of 
breaking the grain. 

There are two general methods of making light dough : — 
i. By non-fermentation methods. 
2. By fermentation methods. 

1. NON-FERMENTED BREAD 

There are a large number of methods used for making 
dough without the use of yeast. Unleavened bread is 
the simplest form of this food and is made without any 
aeration, by mixing the flour and water and baking. Ex- 
amples of this kind of bread are the passover cake of the 
Israelites, the sea biscuit and hard tack used on shipboard 
and in the army, the Scotch oat cake, and the corn-meal 

201 



202 SANITARY AND APPLIED CHEMISTRY 

" pone " so extensively used in the South. Graham and 
whole-wheat flour are used in the same way, thus making 
a bread that is claimed to be more wholesome, and which 
may be kept for a much longer time than the ordinary 
raised bread. Unleavened bread is not, however, con- 
sidered as appetizing as raised bread, but has the advan- 
tage that on account of its hardness and dryness it must be 
thoroughly masticated and mixed with the saliva, and 
thus becomes the more readily digested. 

The object of these processes for making the dough 
light without the use of yeast is to shorten the time and 
labor of making the bread. The following methods may 
be noticed, and will serve to show that much thought has 
been devoted to the subject. 

ENTRAPPING AIR 

1. By mixing Graham flour or wheat flour with water, 
or milk, and beating it vigorously for some time, and 
baking quickly in cast-iron pans, a fairly light bread results. 
The raising- substance in this case is the air that is en- 
trapped hi the dough. Gems and muffins are made in this 
way in some dietary establishments. 

2. A modification of the above plan is to mix the mate- 
rials with snow, and then bake quickly in a hot oven. In 
this case the cook depends on the air that is entrapped in 
the snow crystals to raise the dough. 

3. Eggs, beaten to a froth, will entangle sufficient air 
to make dough very light and spongy. This fact is 
taken advantage of in the making of sponge cake. 

ADDITION OF A VOLATILE SUBSTANCE 

4. Brandy, wine, or any liquor, diluted, may be used 
instead of the water, in the mixing of dough, and when this 



BREAD 203 

is baked the expansion and volatilization of the alcohol 
will raise the dough. It is probable that very little of the 
alcohol will remain in the finished product, but there are 
some objections to this method, both on account of its ex- 
pense, and because of the flavor imparted to the product 
by the liquor that remains. 

5. Ammonium carbonate, (NH^COs, is an extremely 
volatile substance, and if a solution, or the fine powder, 
be mixed with the flour, it will, as it escapes in the process 
of baking, raise the dough. This has been used with 
yeast, by the baker, to obtain very light bread. The 
ammonia salt is also used to overcome any excess of acids 
due to the overfer mentation. 



ADDITION OF SUBSTANCES WHICH EVOLVE CARBON 
DIOXID 

6. Sodium bicarbonate (NaHC0 3 ), when heated, gives 
off a part of its carbon dioxid gas and some water ; and 
as this escapes it will render the dough light. There is, 
however, a great disadvantage in the use of this substance, 
as there remains in the bread sodium carbonate, an alka- 
line substance that renders the bread unwholesome. 

7. A modification of this process, however, will give 
an excellent product. If the baking soda is used with 
molasses, which usually contains some free acid, then the 
alkali is neutralized, and carbon dioxid is set free, and the 
material is very light. This is taken advantage of in 
making gingerbread. If the molasses is not sufficiently 
acid, a little vinegar may be added to it. 

8. Aerated bread, as made by Dr. Dauglish, an Eng- 
lish physician, in 1856, was introduced a few years ago, 
and for a time seemed to be so popular in this country 



204 SANITARY AND APPLIED CHEMISTRY 

that there was a prospect of its replacing the other varieties 
that were on the market, but it has not found favor here 
in recent years. It is used extensively abroad, especially 
in London. It possesses a characteristic taste that is 
entirely different from that of fermented bread. In the 
manufacture of this bread the flour is mixed in a strong 
iron vessel, provided with a mechanical stirrer, with salt, 
and water that is impregnated with carbon dioxid gas. 
The dough is forced out of the apparatus by the pressure 
of the gas, and is molded into loaves, that are immediately 
placed in the oven. The vesiculation is produced by the 
carbon dioxid gas, which, in its efforts to escape, raises the 
dough. There is no chemical change in the flour, as in 
fermentation methods of making bread, and so none of the 
flour is lost in the process. 

9. A process that is somewhat allied to this, but one 
that has not been received with very much favor, is to 
mix the flour with baking soda, and then to add to the 
water that is to be used in the mixing of the bread sufficient 
hydrochloric acid to combine chemically with the soda; 
and in this way there would be left in the bread nothing 
but common salt, in accordance with the equation : — 

NaHCOs+HCl = NaCl+H 2 0+C0 2 . 

10. By the use of sodium bicarbonate and freshly 
curdled sour milk, excellent results may be attained. In 
this case, there is left in the bread sodium lactate, an 
entirely harmless salt, and carbon dioxid gas is set free. 
Some skill is of course required to get sufficient soda in the 
material to exactly combine with the acid of the milk. 
One teacup of sour milk will usually neutralize a teaspoon- 
ful of baking soda. If the milk is not acid enough for the 
purpose, it may be acidified still further by the addition of 



BREAD 205 

some vinegar. Biscuit and cakes are not only raised by 
this process, but they are rendered richer by the fat and 
the casein of the milk. If too much soda is added, the 
product is, of course, yellow, alkaline, and unwholesome. 
The equation is : — 

NaHC03+C2H 5 OCOOH = C 2 H50COONa+H 2 0+C02. 

Lactic Acid Sodium Lactate 

11. Sodium bicarbonate and cream of tartar are often 
used to render dough light. The first of these may be 
mixed with the flour, and the latter with the water that is 
used in mixing the dough, or both may be sifted and mixed 
with the flour. This is an excellent method, as the only 
salt remaining in the bread is " Rochelle salt," a compara- 
tively harmless substance, though in large quantities it 
acts as a laxative. The proportions of each substance to 
be used, as estimated from the molecular weight, are one 
part of sodium bicarbonate to two parts of cream of tartar. 
As the powders do not differ very much in bulk, they may 
be measured with a teaspoon. The equation representing 
the reaction that takes place is as follows : — 

KHC 4 H40 6 +NaHC03 = KNaC4H 4 6 +C02+H 2 0. 

The tartrate is made from " argols," that are collected in 
the bottom of wine casks in the process of fermentation. 

12. By the use of baking powders. These powders 
are of four kinds : — 

1. Cream-of -tartar powders. 

2. Phosphate powders. 

3. Alum powders. 

4. A mixture of alum and phosphate powders. 



206 SANITARY AND APPLIED CHEMISTRY 

The use of baking powders is more common in the United 
States than abroad. It is said that the amount consumed 
in one year will amount to more than 50,000,000 pounds. 
The only thing added to the soda and cream of tartar or 
other substance furnishing the " acid " in the manufacture 
of a baking powder is some starch or flour, which is 
known as a " filler." This is said to be necessary to pre- 
vent the ingredients from combining too soon. In all the 
powders baking soda is used to afford the requisite amount 
of carbon dioxid gas, the only difference between them 
being in the acid salt or chemical used to set it free. 

STRENGTH OF BAKING POWDERS 

The value of a baking powder depends on the per cent 
of carbon dioxid gas that is set free when the powder is 
put into water. 

The amount of available carbon dioxid obtained from 
a powder may depend not only on the quality of the 
constituents, the skill with which they are mixed, and their 
correct proportion, but also largely upon the age of the 
powder. The bicarbonate of soda and the acid potassium 
tartrate in the cream-of -tartar powders, or the bicarbonate 
of soda and the sodium sulfate, or the alum, in the so- 
called alum powder, will gradually combine, especially if 
they are not absolutely dry, as long as powder is kept in 
stock, and so the strength of the powder will be diminished. 
Of the thirty-one samples of baking powder examined 
by the author, six were cream-of -tartar powders, two phos- 
phate powders, fifteen alum-phosphate and eight alum 
powders. The amount of available carbon dioxid varied 
from 1.41 % to 15.29 %. 

Experiment 104. To show the evolution of carbon dioxid 
from a baking powder, place some of it in a 250 cc. flask, pro- 



BREAD 207 

vided with a cork through which passes a delivery tube having 
its outer end below the surface of 100 cc. of limewater placed 
in a beaker. When water is added to the baking powder, the 
gas is rapidly evolved and produces a precipitate in the lime- 
water : — 

Ca(OH) 2 + C0 2 + = CaC0 3 + H 2 0. 

Experiment 105. Test a baking powder for flour or starch 
as mentioned in Experiment 93. 

A powder of the cream-of-tartar class by a complete 
analysis would show the following constituents : x — 

Per Cent 

Total carbon dioxid (C0 2 ) 12.25 

Sodium oxid (Na 2 0) 11.03 

Potassium oxid (K 2 0) 11.71 

Calcium oxid (CaO) .19 

Tartaric acid (C 4 H 4 6 ) 35.14 

Sulfuric acid (S0 3 ) 12 

Starch 18.43 

Water of combination and association, by difference . 11.13 

100.00 

The available carbon dioxid was found to be 11.13 %. 
This powder would then be made from about 25 parts 
of sodium bicarbonate, 50 parts of cream of tartar, and 
25 parts of starch. The small quantities of other sub- 
stances are accidental impurities in the chemicals used. 
Sometimes a little ammonium carbonate is used with the 
above powder. As this is really a mixture of ammonium 
carbamate and carbonate, the reactions at first would 
be: — 

NH 4 C0 2 NH 2 = 2 NH 3 + C0 2 . 

Ammonium Carbamate Ammonium Carbonate 

and (NH 4 ) 2 C03 = 2 NH 3 + H 2 + C0 2 . 

1 Bui. 13, Pt. 5, U. S. Dept. Agric, Div. Chem. 



208 SANITAKY AND APPLIED CHEMISTRY 

Therefore the ammonia salt is entirely volatilized by 
the heat of the oven. 

Experiment 106. To test a baking powder for ammonium 
carbonate, place about 15 g. in a beaker, and over this put 
a watch glass carrying on its under side a moistened slip of red 
litmus paper. If the beaker is warmed carefully on an iron 
plate or stove, the ammonia, if present, will, after some time, 
color the paper blue. 

Experiment 107. To test for tartaric acid or a tartrate in a 
baking powder, place about 10 g. in a beaker, add water, and 
after a short time filter off the starch and insoluble material. 
To the filtrate add a little copper sulfate solution and some so- 
dium carbonate, and boil the solution for a few minutes. Filter 
off any copper hydroxid that may be present and dilute the 
filtrate about four times. If the solution is a distinct blue, 
especially after adding more sodium carbonate and boiling again 
and filtering, this indicates the presence of tartrates. 1 

13. Phosphate powders are made from the acid phos- 
phate of lime, — often called superphosphate, — sodium 
bicarbonate, and starch. The phosphate is made by the 
action of sulfuric acid on bones, consequently it some- 
times contains a little calcium sulfate, but a small quantity 
is not considered an adulteration. The reaction that 
takes place is as follows : — 

CaH 4 (P0 4 ) 2 +2 NaHC0 3 = CaHP0 4 +Na 2 HP0 4 +2 C0 2 

+2 H 2 0. 

The substances that are left in the bread are considered 
about as harmless as the Rochelle salts, and are by some 
thought to be of actual value to the system. On analy- 
sis these powders are shown to have the following com- 
position : 2 — 

1 Bailey and Cady's "Qualitative Analysis," 8th ed., p. 186. 

2 Bui. 13, Pt. 5, U. S. Dept. Agric, Div. Chem. 



BREAD 209 

Per Cent 

Total carbon dioxid (CO) 2 13.47 

Sodium oxid (Na 2 0) 12.66 

Potassium oxid (K 2 0) .31 

Calcium oxid (CaO) 10.27 

Phosphoric acid (P 2 5 ) 21.83 

Starch . . . _ 26.41 

Water of combination and association, by difference . 15.05 

100.00 

Available carbon dioxid 12.86 %. This powder would 
be made up of about the following ingredients : — 

Per Gent 

Sodium bicarbonate 26 

Acid calcium phosphate 37 

Starch 27 

Water of association, etc 10 

Experiment 108. To test for phosphoric acid, ignite about 
5 g. of the powder in a porcelain dish, heat the residue with 
nitric acid, dilute, and filter. To the nitrate add ammonium 
molybdate, and warm (do not boil), when the formation of an 
abundant yellow precipitate of ammonium phosphomolybdate 
shows the presence of phosphoric acid. It should be remembered 
that the ash of flour will show a small quantity of this acid. 

14. Alum powders are often mixed with phosphate 
powders, and Professor Mallet states that he finds 
that this is usually the case. The alum used is soda 
alum, if this is the cheapest, though sometimes " cream-of- 
tartar substitute " (calcined double sulfate of aluminum 
and sodium) is used. If alum is used, the equation would 
be: — 

2 NH4A1(S0 4 ) 2 + 6 NaHC0 3 = 2 Al(OH) 8 + 3 Na 2 S0 4 

+ (NH 4 ) 2 S0 4 + 6C0 2 . 

The analysis of a powder of this class shows the follow- 
ing constituents : l — 

1 Loc. cit. 
P 



210 SANITAKY AND APPLIED CHEMISTRY 

Per Cent 

Total carbon dioxid (C0 2 ) 7.90 

Sodium oxid (Na 2 0) 6.99 

Calcium oxid (CaO) .12 

Aluminum oxid (Al 2 3 ) 3.65 

Ammonia (NH 3 ) 1.02 

Sulfuric acid (S0 3 ) 10.11 

Starch 45.41 

Water of combination and association, by difference . 24.80 

100.00 
Available carbon dioxid 6.41 

This powder would, therefore, be made from about the 
following constituents : — 

Per Cent 

Sodium bicarbonate 21 

Ammonia alum (anhydrous) 15 

Starch 45 

Water of crystallization and association 19 

In this particular powder the amount of available carbon 
dioxid is low, but this is probably because the powder had 
been in stock for some time. Alum powders will give as 
much available carbon dioxid as any others. 

Many experiments have been made to decide exactly 
what is left in the bread when alum and phosphate powder 
is used. From these investigations it is shown that the 
powder which contains enough phosphate to combine with 
the alum is a better powder than the one consisting of 
alum alone. This is so because the phosphate is less 
liable to be soluble than the hydrate of aluminum. It was 
also proven that the interior of a loaf of bread seldom 
reaches the temperature of 100° C, and, on this account, 
the aluminum hydrate will not be dried sufficiently to 
render it insoluble. Professor Mallet says : " A part of 
the aluminum unites with the acid of the gastric juice 
and is taken up into solution, while at the same time the 



BREAD 211 

remainder of the aluminum hydroxid, or phosphate, 
throws down, in insoluble form, the organic substance 
constituting the peptic ferment/ ' l From experiments 
made upon himself, he concludes that aluminum hydroxid 
taken into the system tends to produce indigestion. See 
also more recent experiments made under the direction of 
the U. S. Dept. of Agriculture. 

Experiment 109. To test for sulfuric acid, ignite about 
10 g. of baking powder in a porcelain or platinum dish, cool, 
and boil in a beaker with strong hydrochloric acid until nearly 
all dissolved; dilute with water, filter, heat nearly to boiling, 
and add barium chlorid. The formation of a fairly abundant 
precipitate of BaS04 indicates sulfuric acid. 

Experiment 110. If sulfuric acid has been found, alumina 
is probably also present. To test for this, apply the logwood 
test mentioned in Experiment 117. 

Experiment 111. Another test for aluminum salts in bak- 
ing powders, that may be applied even in the presence of phos- 
phates, is to burn about 2 g. of the powder in a porcelain or 
platinum dish, extract the ash with boiling water, and filter. 
Add to the filtrate enough ammonium chlorid solution so that 
the mixture shall smell distinctly of ammonia. The appear- 
ance of a white, flocculent precipitate, especially on warming, 
indicates the presence of alumina. The equation is : — 

Na2Al 2 4 + 2 NH 4 C1 + 4 H 2 

= 2 Al(OH) 3 + 2 NH4OH + 2 NaCl. 

Calcium phosphate would be insoluble in the water, 
and alkaline phosphates would be precipitated only when 
alumina was present. 2 

Experiment 112. To test for alum in cream of tartar, add 
to the sample an equal quantity of sodium carbonate, burn 
the mixture, and treat the ash as in the preceding experiment. 

1 Loc. cit. 

2 Leach, 31st Ann. Rep., Mass. State Bd. Health, 1899, p. 638. 



212 SANITARY AND APPLIED CHEMISTRY 

Experiment 113. As cream of tartar is often adulterated 
with calcium phosphate, to test for this impurity, ignite a 
sample of the cream of tartar and proceed as in Experiment 
108. 

Experiment 114. Ammonium carbonate may be detected 
in a baking powder by mixing it with a little water, and sus- 
pending in the beaker, which should be covered with a watch 
glass, a piece of moistened red litmus paper. After a time 
this will become blue if ammonia is present. 

Experiment 115. To test for lime in a sample of cream of 
tartar, in the absence of phosphates, ignite, dissolve the ash 
in water, with a little HC1, filter, and add an excess of ammo- 
nium hydroxid, and a few drops of ammonium oxalate. The 
formation of a white precipitate indicates the presence of lime 
(see Experiment 113). 

It is essential that all the ingredients of which a baking 
powder is composed should be well dried before mixing. 
The reason for this is obvious, as without it a partial com- 
bination is liable to take place continuously. Of course 
there is a temptation to add more starch than is essential, 
but an amount of not over 20 to 25% is not considered 
excessive, and less than this is sufficient for the purpose. 

HOMEMADE BAKING POWDER 

An excellent powder for domestic use may be made as 
follows : — 

Lb. 

Cream of tartar, fully dried 1 

Cornstarch J 

Baking soda § 

These materials can be bought at a moderate price, and 
should be dried separately and well mixed, and then kept 
in a dry place. 



BREAD 213 

2. FERMENTED BREAD 

Raised bread is usually made from wheat or rye flour, 
which is made into a paste with water, salt, and yeast. 
There are several ways in which the ferment may be used. 

(a) The first of these methods is by the use of yeast. 

(6) The second is by the use of " leaven/ ' or sour dough. 

(c) The third is commonly known as the " salt-rising " 
process. 

In all of these processes, however, the yeast germs bring 
about the fermentation, the only difference, as will be 
seen later, being the source from which the ferment comes. 

(a) THE USE OF YEAST 

In the ordinary method the yeast is mixed with a little 
warm (not hot) water and flour, or potatoes and salt, and 
thus what is called " sponge " is made. This is allowed to 
rise for some hours, and to it is added more flour, and water 
or milk. Fermentation proceeds, with a continual evolu- 
tion of gas. The gluten which is in the dough retards the 
escape of the carbon dioxid, and the tension of the warm 
gas expands the little cells ; then the dough is puffed up 
and becomes light and spongy. It is molded into loaves, 
and the loaves are set in a warm place until the expansion 
of the gases has raised them somewhat, and they are 
then baked in an oven heated to a temperature of from 
350° to 570° F. The oven should not be too hot at first, 
as in this case the crust that is formed will prevent the 
interior of the loaf from being fully baked, or it will cause 
the loaf to crack open in an unsightly way from the ex- 
panding gases. 

Yeast was known to the ancient Egyptians, and from 
them the Greeks and Romans learned its use. In the 



214 SANITARY AND APPLIED CHEMISTRY 

raising of bread the conditions are favorable first for the 
breaking up of the starch by the diastase of the flour into 
a kind of sugar, and second, by the action of yeast a 
part of the sugar is changed into carbon dioxid gas and 
alcohol. This is represented by thefollowing equations : — 

C 6 H 10 O 5 + H 2 = CeH^Oe ; C 6 H 12 6 = 2 C 2 H 6 + 2 C0 2 . 

Starch Sugar Alcohol 

Yeast requires for its growth, sugar, nitrogenous com- 
pounds, and mineral salts. 

Much time and study has been given, by chemists, to the 
cultivation of pure yeasts, and to the cultivation of those 
varieties best adapted to bread and beer making. The 
variety best adapted to bread-making is said to be 
Saccharomyces cerevisice. 

Brewers' yeast, which is one of the best to use for making 
bread, should be fresh and not soured. Compressed yeast 
is made from a by-product of the distilleries. " Top 
yeast " or bottom yeast may be used, but the former is 
considered more desirable for bread-making. This mate- 
rial is pressed and mixed with 5 or 6% of starch. It may 
be wrapped in tinfoil, while still somewhat moist, and 
shipped in a refrigerator. The addition of any con- 
siderable quantity of starch to these cakes is considered 
an adulteration. 

For domestic use, yeast is prepared by the use of flour, 
water, a little salt, yeast, and some mashed potatoes. To 
this is sometimes added water in which hops have been 
boiled, and the whole is allowed to ferment for about 6 
hours. This yeast will keep well in a cool place, but in a 
warm place it ferments rapidly and is soon sour. A yeast 
can also be made by preparing a mixture of flour, water, 
and salt and then, without adding the yeast, allowing the 



BREAD 215 

germs to get in from the air. After a few days, if the mix- 
ture is kept in a warm place, a product will be obtained 
similar to the material made by the use of yeast. 

Sometimes the yeast plant is mixed with corn meal, and 
the dried mass is put upon the market under the name of 
" yeast cakes/ ' These cakes, which will keep almost in- 
definitely, only need to be soaked in warm water to be 
ready for use. 

(b) THE USE OF LEAVEN 

In the use of the leavening, or sour-dough process, 
which has been practiced for hundreds of years, some of 
the dough that has been left over from one batch of bread 
is used in raising the next. " A little leaven leaveneth the 
whole lump." This leaven should be kept in a cool 
place, lest other microorganisms besides yeast plants get 
into the dough, and even then there is often a secondary, 
or lactic, fermentation, so that the resulting bread is sour, 
or has a disagreeable taste. Since compressed yeast 
cakes are to be purchased almost everywhere, this process 
of raising bread is not used as much as formerly. It is 
chiefly used in the raising of rye bread and other coarse 
forms of breadstuff s. 

(c) THE SALT-RISING PROCESS 

The salt-rising process depends on the fact that there 
exist in the various ingredients, especially in corn meal, 
certain bacteria which will grow at a temperature above 
that which is favorable for yeasts and molds. H. A. 
Kohman * has found it practicable to isolate these bac- 
teria, so that under the right conditions they can be used 

1 /. Ind. and Eng. Chem., Vol. 4, 1912. 



216 SANITARY AND APPLIED CHEMISTRY 

as a " starter. " Salt, corn meal, and baking soda are 
stirred into milk heated to boiling. This " sponge " is 
allowed to stand from 12 to 15 hours, and is then mixed 
with flour and water, and the dough is kept at a tem- 
perature of 110° F. for some time. It is then molded 
into loaves and baked. Salt-rising bread is finer grained 
than yeast bread, and has a peculiar and characteristic 
odor, which is due, no doubt, to the lactic fermentation 
which has taken place. 

CAUSES THAT AFFECT FERMENTATION 

Organic acids assist fermentation. 

Mineral acids will destroy the ferment. 

Alkalies stop fermentation. 

Twenty per cent of alcohol stops fermentation. 

Drying does not stop fermentation. 

Boiling destroys the ferment. 

A low temperature hinders fermentation, but does not 
destroy the ferment. 

Alcoholic fermentation takes place best at a temperature 
of from 9° to 25° C. (from 48.2° to 77° F.). The yeast 
plant grows very rapidly, by a process of " budding " ; so 
that often one cell will multiply to eighty in nine hours. 
Above 30° C. butyric fermentation sets in, and the prod- 
ucts are still further changed. Ferments may be kept 
out of a fermentable liquid, or medium, by first sterilizing 
it by heat, then protecting it with a wad of sterilized 
cotton, or even by a capillary tube that is very much 
twisted. 

If the process of fermentation is allowed to go too far, 
the sugar, or some of it, is further decomposed into lactic 
acid, thus : — 



BREAD 217 

C6H12O6 = 2 CsH 6 03, 

Lactic Acid 

and the dough becomes sour. This may also take place, 
in some cases, by the formation of other acids in the mass, 
as the moist dough is a good medium for the growth of 
various ferments besides the yeast plant. 

MAKING GOOD BREAD 

Some of the most important things to be noted in the 
making of good bread : — 

1. Thorough kneading, in order to distribute the sponge 
or yeast well through the mass. Lack of attention to this 
will cause the bread to be coarse grained, and to have 
large holes distributed irregularly through it. 

2. The dough should be allowed to rise sufficiently, so 
that the carbon dioxid gas and the alcohol that are formed 
in the process of fermentation may have an opportunity to 
raise the loaf. In this process, the soluble albumen and 
globulin of the flour become insoluble, and can no longer 
be separated from the starch. It is probable that some of 
the gliadin is rendered soluble. The starch is partly 
changed to soluble carbohydrate, and partly to carbon 
dioxid and alcohol. 

3. In the process of baking, the heat should not be too 
great, at first, but time should be given for the dough to 
dry throughout the whole mass, for the cell walls to be- 
come firm, and for the starch to become well cooked. As 
this heating goes on, while the inside of the loaf is not 
usually heated above 100° C, the outside will gradually 
get hotter, dextrin and some caramel will be formed, and 
the yeast cells will be killed by the heat. Baking renders 
the starch more soluble, and hence digestible. The dex- 



218 SANITAEY AND APPLIED CHEMISTRY 

trin that is formed is sweeter than starch, and as it is more 
soluble, there is reason in the belief that it is a better 
food for invalids than the crumb. It is also necessary to 
masticate toast thoroughly ; that is, if it is eaten dry, so 
the process of digestion will be further assisted. 

Before putting the loaves into the oven, they are some- 
times moistened on the surface, to assist in the prompt 
formation of a crust that shall restrain the loaf in its tend- 
ency to expand too rapidly. If steam is injected into the 
oven during baking, it produces a glazed surface on the 
loaf. The steam given off from the bread when it is first 
put into the oven acts in the same way. In baking, the 
heat also expands the gases given off, and this assists in 
puffing up the dough. 

4. The process of fermentation should not be allowed 
to go too far. If we knew the exact amount of lactic 
acid formed in any case, we might add sufficient sodium 
bicarbonate, known as " baking soda," to neutralize it, 
but as we cannot in practice do this, it is better to regulate 
the temperature carefully, so that the dough does not get 
too light. If too much baking soda is added, the loaf 
will be yellow in color, alkaline, and unwholesome. 

LOSS IN BAKING 

In the process of baking, bread will lose from 15 to 
20 % of its weight. This loss is due to the escape of 
carbon dioxid gas, water, and alcohol. Elaborate 
attempts have been made to collect the alcohol that es- 
capes during the process, but they have so far been 
failures. There is no small amount lost, however, as 
Liebig estimated that in Germany alone 12,000,000 gal. 
of alcohol disappeared yearly in this industry. There 



BREAD 219 

remains in the fresh bread, after baking, about 2 parts 
of alcohol per 1000, and after a week this amount is 
diminished to 1 part per 1000. One author estimated that 
40 2-lb. loaves contained as much alcohol as a bottle of 
port wine. 

BAKING 

A good method for testing the heat of the oven is to 
throw into it some dry flour, and if it soon becomes brown 
the temperature is sufficiently high. The flour should not 
burn, of course, but dextrin should be formed. The 
question naturally arises, Why does not the bread burn at 
this high temperature ? If we remember the large amount 
of moisture and alcohol that are evaporated during the 
process of baking, it is easy to see that for the time, at 
least, much of the heat is used up in driving off these 
substances, and it is not till later in the operation that the 
temperature is high enough to change the starch of the 
outside of a loaf into dextrin. 

In large bakeries the oven is heated to a temperature a 
little above that required to bake the bread (500° F.) at 
first, and when the bread is put in the temperature falls, on 
account of the amount of cold material that has come into 
the oven, and then gradually rises again, even if no more 
fuel is added. Just before a batch is baked more fuel 
is added, to raise the temperature at the close of the 
operation, and to prepare the oven for the next lot. 

In the old-fashioned way of baking in a brick oven, a 
fire was built in the oven, and, when the bricks became hot, 
the fire was removed, the ashes swept out, and the bread 
was baked with the heat that the walls of the oven had 
retained. This method of baking is still used on a large 
scale, especially in England. The Dutch oven, an iron 



220 SANITARY AND APPLIED CHEMISTRY 

pot, with a cast-iron cover, which is kept hot by coals above 
and below, is used for baking where no better appliance 
is at hand. In most large bakeries crackers are baked on 
the swinging shelves of a horizontal cylinder that slowly 
moves above a smokeless fire. About twenty minutes is 
required for baking a batch, which is put into the oven at 
the same point where the previous lot was removed. The 
swinging shelves are so arranged that the heat is uni- 
formly distributed under the revolving wheel, and by a 
mechanical arrangement any point of this wheel may be 
brought in front of the charging door. 

FRESH VS. STALE BREAD 

That there is a difference between fresh bread and that 
which is several days old is very apparent. What this 
difference is was for some time a question. It was 
formerly said that this difference was due solely to the loss 
of water, but that is proved not to be the case, as there is 
nearly as much water in bread after several days as when 
the bread is fresh, and if stale bread is reheated it becomes 
for the time fresh again. It has been suggested that in 
fresh bread some free water is present, which becomes 
united with the starch or gluten as the bread grows stale, 
and that reheating sets it free again. It has also been 
stated that the difference is only a " molecular one." 
Stale bread still contains about 45 % of water. The true 
theory may be that as bread dries the fibers gradually 
approach nearer to each other by shrinkage, and the walls 
of the thousands of pores are consolidated, and the size 
of the pores is thus increased. When the stale bread is 
heated, expansion occurs ; by the conversion of some of 
the water into vapor, the adhesion between the fibers is 



BREAD 221 

broken up, drawing them apart in the direction of the 
least resistance, producing an apparent diminution in the 
porosity. 

A great impetus was given to the baking industry by the 
Vienna Baking Exhibit at Philadelphia, in 1876. Bread 
furnished by the bakers at present is a better imitation of 
the domestic bread, and hence is more palatable, than that 
formerly made. 

COMPOSITION OF BREAD 

From 100 lb. of flour it is possible to make 135 to 150 
lb. of bread, or, it may be stated, that from f lb. of flour 
it is possible to make 1 lb. of bread. If dry flour contains 
16 % of water, when this is made into bread it gives the 
composition : flour, 84 parts ; water, 16 and 50, making 
150 parts. The water is retained by the gluten cells. A 
flour that contains only a little gluten will not make a good 
strong dough. Bakers take advantage of this, and to 
make a strong dough, that will rise well, they mix hard 
and soft wheat in such proportions as will give a dough 
that is rich in gluten. When considered with reference to 
the amount of gluten, the following analysis of bread 
is of interest : — 

Per Gent 

Water 40 

Gluten 7 

Starch, sugar, and gum 51 

Salts _2 

100 

From Bulletin 13, Part 9, of the Bureau of Chemistry, 
United States Department of Agriculture, the following 
analyses are quoted : — 



222 



SANITARY AND APPLIED CHEMISTRY 





« 
02 


go 
o x 


o 

W « 




EH 


W 


Carbohy- 
drates, 
excluding 
Fiber 




a 




WW 






02 


Vienna bread .... 


38.71 


8.87 


1.06 


.62 


.57 


1.19 


53.72 


Homemade bread 




33.02 


7.94 


1.95 


.24 


.56 


1.05 


56.75 


Graham bread . . 




34.80 


8.93 


2.03 


1.13 


.69 


1.59 


53.40 






33.42 


8.63 


.66 


.62 


1.00 


1.84 


56.21 


Miscellaneous bread 




34.41 


7.60 


1.48 


.30 


.49 


1.00 


56.18 


Biscuits or crackers 




7.13 


10.34 


8.67 


.47 


.99 


1.57 


73.17 


Rolls 




27.98 


8.20 


3.41 


.60 


.69 


1.31 


59.82 







For comparing the " crumb " and the " crust," we have 
the following analyses, calculated from anhydrous 
bread : — 







Nitrog- 
enous 


Dextrin 
and Sol. 
Starch 


Sugar 


Fat 


Starch 


Water in 

Original 

Bread 


Crumb . . 
Crust . . . 


11.29 
10.97 


14.97 
16.09 


4.17 
4.15 


1.68 
.71 


67.87 
68.07 


40.60 
13.00 





A great variety of products is now put on the market 
by the cracker factories. These include such brands as 
" pilots," made without yeast, but with hot water, lard, 
flour, and salt ; " sodas," made by the use of flour, yeast, 
and lard, or cottonseed oil ; " wafers," made by the use 
of butter, sugar, vanilla, flour, and baking powder; and 
" snaps," made from sugar, flour, lard, baking powder, 
and ginger. 



NUTRITIVE VALUE OF BREAD 

Starch alone is not sufficient to sustain life, for the nitro- 
gen, to assist in building up the tissues of the body, must 



BREAD 223 

also be obtained from some organic source. One fact not 
to be lost sight of is that man does not live " by bread 
alone/ ' He does make use of a large amount of nitroge- 
nous food, in the shape of beef, milk, eggs, etc. ; so it is not 
absolutely necessary that the wheat or other grain should 
furnish sufficient nitrogenous material to sustain life. In 
the modern processes of milling, the first and second grades 
of flour are really rich in proteins. The bran that man 
may have discarded is used by the lower animals for food, 
and so in the beef, pork, and mutton we get the proteins 
that are necessary. Man chooses to allow the animal to do 
this concentrating for him, and thus he has the advantage 
of a mixed diet. 

Some so-called Infants' Foods are principally starch, 
and when fed to infants are practically useless, as the 
starch-converting ferments of the pancreatic juice are not 
secreted till about the end of the first year. 1 

Bread must be regarded as one of the most nutritious 
of foods. It yields to the blood a large quantity of 
carbohydrates, considerable proteins and mineral salts, 
and but very little fat. When it is eaten with butter, 
the deficiency of fat is made up ; we also eat bread with 
meat, and thus the lack of proteins, which would be neces- 
sary to make bread a perfect food, is supplied. Bread and 
milk is a better balanced ration than bread alone, as the 
milk furnishes both protein and fat to supplement the 
deficiency. 

VARIETIES OF BREAD 

Many experiments have been made, and much has been 
written, on the relative value of white bread and bran, 
Graham, and whole-wheat bread. Even if sometimes 

1 Cotton's "Anatomy, Physiology, and Hygiene of Childhood." 



224 SANITARY AND APPLIED CHEMISTRY 

the whole-wheat bread does contain more proteins, they 
are in such a form that they cannot be readily acted upon 
by the digestive juices and so there seems to be less 
absorption of them than in the case of white bread. Artifi- 
cial digestion experiments confirm this opinion. 1 Then, 
too, the coarser breads are liable to produce some irrita- 
tion in the intestines, and this prevents perfect digestion 
and absorption of the food. 

Graham flour is properly made from thoroughly cleaned 
wheat, ground, but not bolted. Some millers claim that 
they can get better results by the use of the old style burr 
stones than by the roller-mill process. The term " entire 
wheat " flour is a misnomer, as in this product the outer 
or branny covering of the grain has been removed and is 
not a constituent of the product. 

Many attempts have been made to perfect a flour, 
richer in proteins, and better adapted than ordinary flour 
to sustain animal fife. Such attempts are the mixing of 
pease meal and of casein with flour, and the use of milk 
in making the bread. There are also many so-called 
" germ flours " on the market, and if it is proved that they 
are well absorbed, this may help to solve the problem. 

It is probably true that the second grade of flour will 
make a more nutritious bread than the highest " patent." 
If stale bread is rebaked, it becomes, for the time, fresh 
again. It is a well-known fact that stale bread has the 
reputation of being more wholesome, and this is founded on 
reason, because fresh bread has a tendency, when masti- 
cated, to roll together in doughy masses that are not readily 
attacked by the digestive fluids. Stale bread retains its 
porosity, to a large extent, while it is being mixed with the 
saliva. 

1 Snyder, U. S. Dept. Agric, O. Ex. Sta., Bui. 101. 



BREAD 225 

In addition to wheat bread, a brown bread, made from 
wheat and Indian meal, or rye and Indian meal, is much 
in favor in some localities. The addition of rye or wheat 
to corn meal assists very much in the raising of the dough, 
because there is not sufficient gluten in the meal to make 
a strong dough that will retain the gas bubbles. The 
properties of flour from the other grains are discussed 
elsewhere. 

BAD BREAD 

Bread may be bad for several causes. Among these 
may be mentioned the following : — 

1. It is bitter, from an abnormal growth in the flour, 
or from the grain being partly spoiled. 

2. It is heavy, from being imperfectly baked, or from 
the use of poor yeast, or from not being allowed to rise 
sufficiently before being placed in the oven. 

3. The flour may be deficient in gluten, from bad 
milling, or from the " growing" of the wheat before it 
was ground. In this case light bread cannot be made, as 
the dough does not possess sufficient tenacity to cling 
together and hold the gases that are evolved. 

4. The bread may be sour from overfermentation, or, 
what amounts to the same thing, from allowing the fer- 
mentation to proceed at too high a temperature. There 
is no excuse for this, as it simply denotes carelessness or 
ignorance. 

5. Bread may be moldy if it is kept in a damp place or 
if it is kept too long. This mold is due to the growth 
of microscopic plants that find the moist bread a fertile 
medium. These molds may be white, green, orange, or 
black. They are supposed by some to be poisonous and to 
produce severe disorders, but even if that is not the case 
they render the bread unfit for use. 

Q 



226 SANITABY AND APPLIED CHEMISTRY 

The center of a loaf of bread is sometimes the feeding 
ground for these lower organisms, 1 especially in very warm 
weather, because the heat of the oven has not been suffi- 
cient to entirely sterilize the interior, and so the bread 
spoils. The texture of the loaf will be changed so that 
it will be stringy and a disagreeable odor is emitted. 

6. The bread may be of a dark color, though not made 
from lower grades of flour. This is due to the change that 
has taken place in the grain or in the flour by its being wet 
and allowing the starch to change to dextrin, gum, or 
sugar. This is practically what takes place in the malting 
of grains. 

ADULTERATION OF FLOUR AND BREAD; COMPOUND 

FLOUR 

The most common adulteration of wheat flour in the 
United States is the addition to it of other flours, espe- 
cially that of corn and possibly rice. This can be readily 
detected by the use of the microscope. The government 
requires all such flours to be labeled " Compound/ ! and 
to pay a revenue tax of 4 cents per barrel. 

As white bread commands a better price than dark, and 
as there is always a greater demand for white bread, 
various attempts have been made to make a white bread 
from a low grade of flour. Substances used for this 
purpose formerly constituted the chief adulteration to 
which flour was liable. In Europe copper sulfate and alum 
had been used, but in many countries their use is now 
prohibited by law. Even so small a quantity as 1 part of 
copper sulfate in 10,000 parts of flour is said to be sufficient 
to enable the baker to make a white bread from a low 
grade of flour. The use of this chemical is condemned 

l Chem. Abs., II, p. 1168. 



BREAD 227 

on account of the poisonous nature of the salts of 
copper. 

Liebig states that the alum makes insoluble the gluten 
that has before been rendered partially soluble by the 
acetic and lactic acids that were developed in the process 
of fermentation. In this way the change from starch to 
dextrin or sugar is arrested. There is a difference of opinion 
as to the effect of alum upon the system, but the most 
reliable testimony is that as the loaf is not heated much 
above 100° C. the alumina will not be rendered insoluble. 
In that case it will go into the circulation and thus tend 
to injure the system. The amount of alum used is not 
over 1| to 3 ounces to 100 lb. of flour. 

Experiment 116. To test for copper sulfate some of the 
bread may be ignited in a porcelain dish with nitric acid, and 
the ash that is left is boiled with a few drops of nitric acid, 
diluted and filtered. To one half of the filtrate an excess of 
ammonium hydroxid is added, and a blue coloration will indi- 
cate the presence of copper. The other half should be neutralized 
with sodium hydroxid, made slightly acid with acetic acid, 
and tested by means of potassium ferrocyanid. The appear- 
ance of a reddish color indicates copper. 

Experiment 117. To detect alum in flour, the logwood test 
has been found very satisfactory. Fifty grams of flour are 
mixed with 50 cc. of distilled water, and to this is added 5 cc. 
of a freshly prepared logwood solution, and the whole is made 
alkaline with 5 cc. of a solution of ammonium carbonate. With 

as small a quantity of alum as the color of the solution 

will be lavender blue, instead of a dirty pink. It is well to set 
the mixture aside in a warm place for 2 hr., and notice if the blue 
color is permanent. 

Experiment 118. To test for alum in bread, add to 50 cc. 
of water 5 cc. of logwood solution and 5 cc. of ammonium car- 



228 SANITARY AND APPLIED CHEMISTRY 

bonate solution. Soak about 10 g. of the crumb in this for 5 
minutes, pour out the liquid, and dry the bread at a gentle 
heat. If alum is present the lavender or dark blue color will 
appear, but if the bread is pure it will turn to a dirty brown 
color. As alum is not often used in flour in this country, these 
tests may be made with some of the " self -rising " flours, which 
usually contain alum, or upon cakes made from this flour. 

Ergot is sometimes found in flour, especially in that 
made from rye. This is due to the " spurred rye," as it 
is called, or really to a fungus growth that is found on the 
grain. It is poisonous, and sometimes has proven in- 
jurious to the lower animals. 

There is very little danger, in the United States at least, 
of the adulteration of flour with clay, chalk, terra alba, 
or any such materials. 

Recently the process of bleaching flour has been intro- 
duced. For this purpose oxides of nitrogen, hydrogen 
peroxid, or chlorin gas are generally employed. The ob- 
ject of bleaching flour is to enable the miller to' make 
more white flour from the grain. Opinions are divided as 
to the wholesomeness of flour treated in this way, but the 
consumer is at least entitled to know from the label if the 
flour has been bleached. 

Experiment 119. Put a sample of flour into a large bottle 
and cover with gasoline. If the flour is unbleached the solution 
becomes yellow, if bleached it remains colorless. 



CHAPTER XV 
PREDIGESTED AND SPECIAL FOODS 

INFANT'S AND INVALID'S FOOD 

Foods for infants and invalids are made up largely of 
cereals which are modified by application of heat, by 
digestion with malt or diastase, and by malting the cereal, 
adding cream or milk, and evaporating. Among those 
prepared by heat alone may be mentioned Blair's and 
Imperial Granum; Mellin's and Horlick's foods are 
representatives of the class that is made by mixing wheat 
flour with malt and a little potassium carbonate, moisten- 
ing with water and heating at a fixed temperature for 
several hours. 1 The starch of the flour is by this process 
changed to maltose and dextrin, which are soluble sub- 
stances. In making the malted cream foods, the flour is 
made into dough, baked, ground, and malted, mixed with 
cream, and evaporated to dryness in a vacuum. Foods 
of this class, such as Malted Milk and Nestle's Food, are 
richer in fat and albumen than the others mentioned. 2 

The following analyses quoted by Hutchinson give 
the composition of some of the well-known Proprietary 
foods : — 

1 Canadian Dept. of Inland Rev., Bui. 59. 

2 "Davis's Chemistry for Schools," p. 285, from Kdnig. 



229 



230 



SANITAET AND APPLIED CHEMISTRY 



Name 


Water 


Protein 


Fat 


Carbo- 
hydrate 


Mineral 
Matter 


Dried human milk 
Horlick's malted milk 
Carnrick's soluble food 
Nestles milk food 
Mellin's food 




3.7 
5.5 
5.5 
6.3 
7.9 
10.4 
10.1 


12,2 
13.8 
13.6 
11.0 
7.9 
9.2 
11.3 
5.1 


26.4 
3.0 
2.5 
4.8 
trace 
1.0 
1.6 
3.9 


52.4 
76.8 
76.2 
77.4 
82.0 
81.2 
75.0 
82.0 


2.1 
2.7 
2.2 
1.3 
3.8 


Ridge's food 




0.7 


Robinson's groats 
Robinson's patent barlej 


T 


1.7 
1.9 



BREAKFAST FOODS 

Breakfast foods and " predigested " foods have recently 
been introduced, ostensibly to take the place of foods 
improperly prepared, and to assist digestion. That there 
is a popular demand for foods of this kind there is no doubt, 
but their extended use is only another illustration of the 
tendency in the United States to allow some one else to do 
the work of the household for us, even though the food 
thus prepared may be expensive and unsatisfactory. The 
statements made on the package usually have nothing to 
do with the value or digestibility of the food. The price 
at which they are sold also bears no relation to the weight 
of the package or the nutritive value. 

In discussing the popular " breakfast foods " a promi- 
nent writer says : — 

" This craving for something new to stimulate a jaded 
appetite, already spoiled by endless variety and bad combi- 
nations, has led to the manufacture of a cereal preparation 
for nearly every day in the year. No better comment on 
the laziness or willful ignorance of the American providers 
could be made than this. Little do the people know about 
wheat or cooking if they suppose that grain can be changed 
by manipulation in any kind of machine so as to give a 



PREDIGESTED AND SPECIAL FOODS 231 

greater food value than was contained in the grain. While 
it is true that some of these preparations are far better 
than the half-cooked grains found on so many tables, 
the fact remains that it is the cook and not the substance 
which is poor. It is not always best to have food that is 
too easily digested. 

" A predigested food is quickly absorbed into the circula- 
tion, and hence a small quantity causes a sensation of 
fullness and satisfaction, which, however, soon passes 
away and faintness results. This is especially true of the 
sugar and the dextrins. Frequent meals should go with 
these easily absorbed foods. This rapid digestion is the 
cause of much pernicious eating of sweets between meals, 
which satisfies the appetite for the time being and pre- 
vents substantial quantities of other foods being taken 
at the time when they are offered." l 

It is well to note that the oatmeal sold in bulk is practi- 
cally the same as that sold in packages, only the latter has 
been better protected from vermin and dust. It is true 
that oatmeal contains more protein and fat, and as far as 
the analysis shows, offers a better-balanced ration than 
most of the other foods, but that does not prove that it 
should be used exclusively as a breakfast food. The 
cereals — wheat, barley, corn, and oats — are the chief 
source for the manufacture of all these foods, but they are 
prepared by different processes. 

The analysis of a few typical brands is as follows : 2 — 

1 Richards and Woodman, " Air, Water, and Food," p. 156. 

2 Slosson, Wyoming Exp. Station, Bui. 33. 



232 



SANITAEY AND APPLIED CHEMISTRY 







£ 


0D 




M 




2 




SB 




6 5 

PQ - 








^ z a 

is* 




O 
3 


PO 


« S 


Eh 


P 


W 




« 03 


<1 £ 

OH 


< 
ft 


D 


tn 

< 


3^ H 


Grape Nuts 


8.00 


12.73 


73.78 


1.57 


2.02 


1.90 


$.13 


Malta-Vita 


8.93 


11.84 


73.19 


1.55 


1.82 


2.67 


.11 


F. S. Rolled Avena . . . 


9.68 


18.42 


60.85 


6.88 


2.22 


1.95 


.071 


Ralston' s Health Breakfast 
















Food 


11.07 


12.55 


72.11 


1.72 


1.35 


1.20 


.07| 


Pillsbury's Vitos .... 


11.19 


13.08 


73.44 


1.08 


.58 


.58 


.07 


Pettijohn's Breakfast Food . 


10.43 


12.11 


71.08 


2.50 


2.30 


1.58 


.07 


Quaker Rolled Oats . . . 


9.40 


17.55 


61.56 


7.20 


2.40 


1.89 


.05 


Shredded Whole Wheat . . 


8.91 


11.32 


73.93 


0.87 


3.40 


1.57 


.11 


Vigor 


9.12 


14.46 


69.18 


1.65 


2.38 


3.21 


.15 









From a study of the analysis of a large number of these 
foods, F. W. Robison 1 arrives at these conclusions : — 

" 1. The breakfast foods are legitimate and valuable 
foods. 

" 2. Predigestion has been carried on in the majority of 
them to a limited degree only. 

" 3. The price for which they are sold is, as a rule, 
excessive and not in keeping with their nutritive values. 

" 4. They contain, as a rule, considerable fiber, which, 
while probably rendering them less digestible, at the same 
time may render them more wholesome to the average 
person. 

"5.. The claims made for many of them are not war- 
ranted by the facts. 

" 6. The claim that they are far more nutritious than 
the wheat and grains from which they are made is not 
substantiated. 

" 7. They are palatable, as a rule, and pleasing to the 
eye. 

1 Robison, Michigan Agric. Exp. Station, Div. Chem., 1904. 



PREDIGESTED AND SPECIAL FOODS 



233 



" 8. The digestibility of these products, as compared 
with highly milled foods, while probably favorable to the 
latter, does not give due credit to the former, because of 
the healthful influence of the fiber and mineral matter in 
the breakfast foods. 

" 9. Rolled oats, or oatmeal, as a source of protein and 
of fuel is ahead of the wheat preparations, excepting, of 
course, the special gluten foods, which are manifestly in a 
different class/ ' 

MACARONI 

Macaroni, vermicelli, spaghetti, and other " pastes " 
are made in Italy, France, and Switzerland, from certain 
highly nitrogenous varieties of wheat. They have more 
recently been made in this country. The macaroni 
is made by mixing " semolina " — the hard, flinty part 
of the wheat grain — with the special wheat, making it 
into a paste, and pressing through the bottom of a cylinder 
pierced with holes. The tubes which come through the 
perforations are cooled, cut in lengths, and dried on screens. 

The composition of macaroni, according to Church, 1 
is: — 





Fine 
Variety 


Cheaper 
Variety 


Water 

Albuminoids, etc 

Starch, etc 

Fat 


13.0 
11.1 

73.8 
.9 
.4 

.8 


10.0 

13.5 

70.8 

2.3 


Cellulose 


1.4 


Mineral matter 


2.0 



i Church, "Food," p. 81. 



234 SANITARY AND APPLIED CHEMISTRY 

Macaroni should be well soaked in water before cooking, 
and may very conveniently be served with cheese, which 
adds to its nutritive value. Sir Henry Thompson, 1 in 
speaking of macaroni, says that " weight for weight it may 
by regarded as not less valuable for flesh-making purposes 
in the animal economy than beef or mutton. Most people 
can digest it more easily and rapidly than meat. It offers, 
therefore, an admirable substitute for meat, particularly 
for lunch or the midday meal." 

1 Quoted from W. G. Thompson, "Practical Dietetics," p. 152. 



CHAPTER XVI 

SUGARS 

HISTORY AND CLASSIFICATION OF SUGARS 

Sugar was known at such an early age that the date of 
its discovery is lost. We hear of its use in India perhaps 
earlier than elsewhere. In Europe honey was used for 
sweetening purposes before sugar came into general use. 
The sugar cane was cultivated in the regions adjoining the 
Mediterranean Sea as early as 1148, in the West Indies 
in 1506, and on the North American continent in 1800. 
Sugar was first noticed as a curiosity, then it came into 
use as a medicine, and finally has become a necessary 
part of our diet. Sugar was at first confounded with 
manna, and was supposed to be the dried juice of a plant. 
As it was not well understood, physicians regarded it as 
having an injurious effect upon the system. Honey was 
thought to be more wholesome, because a " natural food." 
We find the price of sugar quoted at 45 cents per pound 
when it first came into use. The amount of sugar used in 
civilized countries is constantly on the increase. 

The sugars have essentially the same food value as the 
starches, as the latter must be converted into dextrin or 
sugar in the process of digestion. As cane sugar must be 
changed into a form of grape sugar before being digested, 
the latter is often Spoken of as a " predigested " form of 
food. Although sugar is an excellent energy producer, 

235 



236 SANITAKY AND APPLIED CHEMISTRY 

and in fact stands at the head of the list, yet an over- 
indulgence in this food, especially in cane sugar, is sure to 
cause flatulent dyspepsia and other disorders. 

Over 17,000,000 tons of sugar are consumed annually 
in the world, and English-speaking nations consume the 
most per capita. In 1910-11 the per capita consumption 
in England was 91 lb. ; in Germany, 48 lb. ; France, 43 lb. ; 
in Italy, 10 lb. ; Servia, 8 lb. ; and in the United States, 
79 lb. The per capita use of sugar in 1914 in the United 
States was 75 lb. 

On account of their importance as food materials sugars 
should be thoroughly discussed, and their composition 
and relations to other nutrients should be well under- 
stood. In general the sugars are recognized by the fact 
that they are readily soluble in water ; that they have a 
sweet taste ; and that they rotate the plane of polarized 
light. 

There are a large number of sugars known to the chemist, 
but up to the present time the property of sweetness has 
not been identified as belonging to any definite molecule 
or to any definite combination. In addition to the sugars, 
there are other substances that are sweet, as, for instance, 
the alcohols and the organic compound Saccharin, C 7 H 6 - 
3 SN, which is about 500 times as sweet as cane sugar. 
The addition of one part of saccharin to 1000 parts of 
glucose renders the latter as sweet as cane sugar. Sac- 
charin is sometimes used to replace sugar for the use of 
diabetic patients, but it has no food value. 

The sugars that are in common use may be divided into 
two general classes : the sucrose, or cane sugar, group, 
having the composition C12H22O11, and the glucoses, or 
grape sugars, having the composition C 6 Hi 2 6 . Sugars of 
both these classes are found under various names in a large 



SUGARS 237 

number of food substances. These two groups are also 
very intimately related, so that by " inversion/' with heat 
and dilute acids, some of the members of the first group 
may be changed to those of the second group. 

Sucrose, C12H22O11 

The most important members of this group are sucrose, 
maltose, and lactose. Sucrose, or cane sugar, occurs abun- 
dantly in roots, grasses, and stems of many plants, as w r ell 
as in fruits. There are, however, only a few plants from 
which it is economical to make sugar. These plants are 
the sugar cane, the sugar beet, sorghum, the maple and 
birch trees, corn stalks, carrots, and sweet potatoes. 
About two thirds of the sugar, as estimated by Wiley, is 
made from the beet, and one third from sugar cane. The 
other sources are of so little importance that they need 
only be mentioned incidentally. Sugar obtained from 
either sugar cane, the beet, or any other of the sources 
mentioned has the same composition, and the chemist 
cannot recognize any difference between the products. 

From 13 % to 20 % of sugar is found in the stalks of sugar 
cane; from 4% to 15% in the sugar beet; sometimes as 
much as 15 % in sorghum ; and the sap of the maple tree 
contains a little over 2 % of sugar. 

SUGAR CANE 

Sugar cane belongs to the family of grasses, of which 
there are many varieties growing in tropical and sub- 
tropical countries, especially in the moist climate of islands 
and the seacoast. The sugar cane is successfully culti- 
vated mainly in Cuba, the West Indies, Louisiana, the 
Philippines, Java, Brazil, and the Hawaiian Islands. The 
cane flourishes best where the mean temperature is from 



238 SANITARY AND APPLIED CHEMISTRY 

75° to 77° F., but it grows fairly well where the mean 
temperature is not below 66° F. Sugar cane is propagated 
not by seeds, but by cuttings. The young cane sprouts 
from the roots each year, and in the United States usually 
three crops are gathered from one setting, so on each 
plantation one third of the space is set with new cuttings 
each year. In the West Indies, however, the sprouts 
that come from the old roots are cut for a series of years 
until at last the plants die, and are then replaced by fresh 
cuttings. There are two processes of extracting the juice 
from the sugar-bearing material. The first is by crushing 
in roller mills, and the second is by diffusion. The former 
process has been used more especially for making sugar 
from cane and the latter from the sugar beet. 

MAKING SUGAR FROM SUGAR CANE 

The average analysis of the ripe cane shows it to contain 
of sugar 18 %, fiber 9.5 %, water 71 % ; but the juice con- 
tains of sucrose 18%, glucose .30%, gums 1.40%, mineral 
salts .30 %, water 80 %. 1 By the best practice about 84 % 
of the juice is extracted from the cane. 

The cane is cut in the fall, and after being stripped and 
topped is passed through a " shredder/ ' to tear it to 
pieces, then several times between heavy horizontal rollers, 
to extract the juice. The " begasse " or crushed cane 
left after pressing is burned as fuel under the boilers. The 
juice in Louisiana does not often contain over 14% of 
sucrose, but in Cuba it may run as high as 18%. The 
juice is passed through a screen to remove suspended 
matter, then nearly neutralized with milk of lime, and 
heated to coagulate the albumen. This is called " def- 

1 Thorp, "Outlines of Industrial Chemistry," p. 388. 



SUGARS 239 

ecation." The lime not only neutralizes the acid, which 
is quickly formed, and thus prevents it from " inverting " 
the sugar, or changing it to uncrystallizable sugar, but it 
unites with the nitrogenous matter and causes it to 
separate. The scum, which contains many of the im- 
purities, is allowed to rise to the surface and is then 
filtered off and pressed to remove as much of the saccharine 
liquid as possible. The pressed filter cake may be used as 
a fertilizer. The juice is often treated with sulfurous 
acid, which is made by burning sulfur, to prevent fermenta- 
tion and improve the color. The juice must, however, 
be left slightly alkaline to prevent inversion. The juice 
may also be filtered through bone black or animal charcoal 
in order to remove the color. 

Formerly the saccharine liquid was evaporated in open 
pans, until it began to crystallize, then emptied into 
shallow tanks and stirred until it was cool. The mixture, 
which contained both molasses and sugar, was placed in 
hogsheads having holes bored in the bottom, so that the 
molasses could drain out. By this process a sugar called 
" muscovado " was produced, which contained from 87 to 
90 % of sucrose. The molasses obtained in this way was of 
good quality, but the process was not economical, as so 
much of the sugar was " inverted " in boiling. 

In the modern sugarhouse the juice is first concentrated 
in " triple-effect " evaporators, which utilize the steam 
given off from one pan to assist in heating the next, and 
are therefore very economical; then the juice, which in 
this way is much concentrated, is run into the vacuum or 
" strike " pan. Usually the entire system of evaporation 
is heated by exhaust steam, and this conduces greatly to 
the economy of the process. 

In the vacuum pan the juice is heated by steam coils and 



240 SANITARY AND APPLIED CHEMISTRY 

the vapor is pumped off, thus reducing the pressure so that 
the sirup will boil at 150° to 180° F. instead of 230° to 
250° F., which would be the case in the open pan. After 
the sugar has boiled to "grain," or until it begins to crys- 
tallize, some more sirup is admitted to the pan and crystals 
of sugar are gradually " built up " until a sufficiently large 
charge is obtained. A vacuum is maintained on the pan 
during the entire operation. 

The mixture of molasses and sugar which is then drawn 
out of the vacuum pan is called masse cuite. A part of it is 
run directly into the " centrifugals," and the rest into a 
" mixer," where it is constantly stirred by mechanical 
means, until there is an opportunity to run it into the 
centrifugals. The latter revolve on a perpendicular axis 
at the rate of about 1200 times per minute. The outside 
or perpendicular wall of the drum is perforated, and by the 
rapid rotation the sirup " flies off " into the space outside 
the drum and runs into a receptacle below. The top of 
the drum is open to facilitate charging and washing, and 
the charge can be dropped out at the bottom, when the 
sirup has been separated from the sugar. The sugar while 
in the centrifugal may be washed by throwing into it 
while running a small quantity of water or a saturated 
solution of pure cane sugar. 

The liquid that has run through the centrifugal together 
with the washing is defecated and again boiled down, 
forming a second masse cuite, from which a " second sugar " 
is obtained, and the process is sometimes repeated to 
obtain a third or even a fourth masse cuite. The second 
sugar is often mixed with the concentrated juice before it 
is run into the vacuum pan, to save time in " building up " 
the grain of the sugar. The impure molasses finally ob- 
tained is run into a cistern and worked up later in the 



SUGARS 241 

season in various ways. Recently it has been found to be 
economical to mix some of this molasses with the feed of 
the mules which are employed on the plantation. 

The object of the sugar boiler is to obtain as large a 
quantity of cane sugar, and as little uncrystallizable or 
" invert " sugar as possible, since the impure molasses is 
of little commercial value. 

The total production of sugar from the sugar cane in 
the United States in 1914 was about 247,000 tons. 1 

MAKING SUGAR FROM THE SUGAR BEET 

It was in 1747 that Marggraf, a German chemist, an- 
nounced that it was possible to obtain a sugar from beet 
juice which was identical with that obtained from the 
sugar cane. Achard, a pupil of his, actually erected a 
factory and made some beet sugar, but, as only 2 or 3 % of 
sugar could be extracted from the beets, it was not a com- 
mercial success. Napoleon I, in 1806, caused a bounty to 
be offered for beet sugar, and thus the manufacture was 
greatly stimulated. At first the beet contained only 6 % 
of sugar, but it has been improved so much by cultivation 
that it now often contains as high as 15 %. The other 
constituents of beet juice embarrassed the sugar boiler 
greatly for some time, but the process of manufacture has 
been so much improved that now these very impurities 
have been made a source of profit. 

Although several methods have been used for extracting 
sugar from the beet, the " diffusion " process has been the 
most successful. According to the German method, the 
beets are cut into fine chips, and are then put into a series 
of large iron vessels, where they are extracted with warm 

i Year Book, 1915, Dept. Agric. 



242 SANITARY AND APPLIED CHEMISTRY 

water. The " battery " of diffusors is so arranged that the 
sweet water, heated to 60° C, may be circulated from one 
vessel to another, until the sugar is practically all removed 
from the chips. These are then dropped out of the 
cylinder. It is again filled with fresh chips, and so con- 
nected as to be made the last of the series of diffusors 
through which the juice is circulating. The exhausted 
chips are used as cattle food, as they are rich in nitrogenous 
matter. After the water has remained in contact with 
one lot of material for 20 minutes, it is drawn through a 
juice warmer before it is brought into the next diffusor. 
Although considerable water is used in this process, and 
the juice must be concentrated somewhat more than when 
extracted by crushing, yet the juice is so much more free 
from foreign nitrogenous substances that the diffusion 
process can be used with greater economy and succcess. 
All but 0.5 % of the sugar is extracted. 1 

The crude juice, which contains about as much sugar 
as the original beet juice, is heated to coagulate the albu- 
minoids, and then lime is added to saturate the free acids, 
and assist in throwing down organic matter. Carbon 
dioxid gas is made to pass through the solution, and the 
latter is then forced through the filter press. Sometimes 
this operation of " carbonation " is repeated. Then the 
juice usually goes to the bone-black filters. Sometimes 
the treatment with lime and carbon dioxid gas, and sulfu- 
rous acids, purifies the juice so that no subsequent treat- 
ment with bone black is necessary. Special care and 
treatment is required to make from the sugar beet a fine 
crystalline sugar which has no unpleasant taste or odor. 

The molasses obtained by this process is boiled down 
for a second sugar and a second molasses. As the latter 

i Thorp, "Outlines of Industrial Chemistry," p. 393. 



SUGARS 243 

contains about 40 % of sugar that cannot be crystallized, 
this is usually recovered by treating with quicklime, prob- 
ably forming a tricalcium saccharate, 1 C12H22O11, 3 CaO. 
This latter salt is filter-pressed to separate the precipitate 
from the sirup and impurities, and this precipitate is used 
instead of lime in the defecation of fresh juice, or it may be 
decomposed by passing carbon dioxid into it. In 1915— 
1916, 862,000 tons of beet sugar were made in the United 
States. 2 

MAPLE SUGAR 

The manufacture of sugar from the sap of the hard 
maple, Acer saccharinum, is quite common in the extreme 
Northern states and in Canada. The sugar season is 
limited to 6 or 8 weeks in the spring. The sap is drawn 
from the trees by " tapping/ ' or making an incision 
through the bark, and arranging a spout to carry the juice 
to a receptacle below. This sap is then concentrated in 
shallow pans over an open fire, skimmed, and strained. 
Good sirup contains about 62% of cane sugar, with 
varying amounts of invert sugar. Maple sugar contains 
about 83 % of cane sugar. 

On account of the agreeable taste, which is due to cer- 
tain characteristic substances, the maple products always 
command a high price in the market. There is therefore 
a temptation to imitate these products, or adulterate 
them. Brown sugar, especially, is often melted with 
inferior maple sugar, while maple sirup is adulterated with 
glucose, molasses, or refined sugar. Hickory bark is said 
to be used as a flavoring material in the imitation maple 
sugars. It is not difficult for the experienced chemist to 
detect the spurious article. 

1 "Industrial Chemistry," Rogers and Aubent, p. 663. 

2 Ann. Rep. Dept. Agric. 



244 SANITARY AND APPLIED CHEMISTRY 

SORGHUM SUGAR 

The juice of the sorghum (Andropogon sorghum) has 
been used for a long time in the United States by the 
farmers as a source of a cheap sirup, and the United States 
Department of Agriculture at one time carried on very- 
extensive experiments, looking to the possibility of making 
a crystallizable sugar from sorghum. The cane has been 
improved so that it often contains 15 % of sugar. Many of 
the difficulties have been overcome by the use of the " diffu- 
sion process " and improved methods of purification of the 
juice. Although a good quality of sugar can be made, 
yet the manufacture can hardly be called a commercial 
success, and practically no sugar is made from sorghum. 

MOLASSES 

Molasses is of various grades, and contains the uncrys- 
tallizable sugar, some cane sugar, gum, coloring matter, 
and mineral salts. Where the drippings from the vessel 
from which the " first " sugar crystallizes are used as 
molasses, we have a very pure product. Since the lower 
grades of sugar are made by evaporation of the drippings 
and washings of the several crystallizations, they contain 
more impurities and more moisture than does granulated 
sugar, and it is a question whether they are really cheaper. 
It is probably on account of its ready solubility in the 
mouth that we get the impression that the impure sugar 
is sweeter. 

SUGAR REFINING 

Since much of the sugar raised on the plantations is put 
on the market in its " raw " condition, it must be refined 



SUGARS 245 

or purified before it is fit for use. Sugar refineries are 
usually situated in the large commercial centers, in this 
country at New York, Philadelphia, New Orleans, and 
San Francisco. The buildings are very high, so that ad- 
vantage can be taken of gravity in handling the product. 
The raw sugar is partially dissolved in molasses in large 
vats, or " melters," placed below the floor of the basement. 
The masse cuite thus formed is run directly into the cen- 
trifugals, where it is slightly washed. The sugar thus 
obtained is " melted " in warm water, strained from the 
coarser particles of dirt, and pumped to the top of the 
building. 

The solution may be " defecated " by boiling with lime, 
clay, alum, calcium phosphates, or with fresh blood from 
the packing house. It is then conveyed to " bag filters," 
made of heavy cotton twill, from 5 to 8 ft. long. Here 
the refuse that would not settle in the defecating tanks 
is collected. The liquor, which is now clear, but of a 
brownish color, is run into the " bone-black filters." 
These filters are long cylinders, often extending through 
several stories, fitted with a perforated bottom over which 
a blanket is spread, to prevent the bone black, with which 
the cylinder is filled, from falling through. 

The sugar solution is allowed to trickle slowly on to this 
filter, and to remain for about 24 hours in contact with the 
bone black; the product first drawn off is the purest. 
When the bone black is exhausted, it is washed with water, 
which, of course, is saved, and the bone black is " re- 
vivified " by being burned in closed retorts. The bone 
black, when it is cold, is sifted and the dust is sold for the 
manufacture of fertilizers. 

The colorless liquor is then ready to be concentrated in 
the "vacuum pan" previously described (p. 239). When 



246 SANITARY AND APPLIED CHEMISTRY 

the masse cuite has crystallized sufficiently to make " loaf 
sugar/ ' it is run into conical sheet-iron molds having an 
opening at the bottom, and the sirup runs off. Then a 
saturated solution of sugar is poured on the top of the 
" sugar loaves " to wash out the uncrystallized material. 
This process of drainage and drying may, however, be 
much shortened by placing several cones at a time in a 
centrifugal, and " throwing out " the sirup by rapid rota- 
tion. 

A modern process of making loaf sugar is to warm the 
granulated sugar from the centrifugals with a saturated 
solution of pure sugar or with a thick sugar sirup, and to 
press this mixture into molds where it is allowed to harden. 

Experiment 120. To show the action of bone black, dissolve 
about 30 g. of brown sugar in warm water, add at least 25 g. 
of bone black, and after shaking the mixture for some time, 
filter. A colorless filtrate should be obtained. The operation 
may be repeated with the filtrate if it is not colorless. 

COMMERCIAL SUGARS 

To make granulated sugar directly, the mixture of sugar 
and sirup, frequently 3500 pounds in a charge, is drawn 
off from the vacuum pan into a mixer, where it is stirred 
while cooling to prevent the grains from sticking together. 
The sugar and sirup are separated in the centrifugal, as in 
the case of making raw sugar, and the sugar is washed with 
fresh water. It is then conveyed to the " granulator," 
which is a rotating cylinder, set at a slight incline, and 
heated by steam. Here the sugar, which enters the upper 
end, is dried, and the grains are separated one from an- 
other, and then pass through a series of sieves, and are 
finally rim into barrels for shipment. The sirups obtained 



SUGARS 247 

in the refining process may be again filtered through bone 
black, and boiled to make lower grades of sugar, or they 
may be mixed with glucose and put on the market directly 
as table sirups. 

To make the granulated sugar from loaf sugar, the 
cones are crushed and sifted, and the crystals passed over 
a heated table into the packing barrels. Usually a little 
" ultramarine " is added to the sugar to correct the 
slightly yellow color. Although this coloring matter is 
not injurious, yet in some manufacturing processes it 
will be found to give a disagreeable odor to the sirup, on 
account of the decomposition of ultramarine by acids. 

Powdered or pulverized sugars are made from the same 
stock as the granulated sugar, but it is ground and bolted 
in a mill similar to that used for making flour. 

Cut sugar is made from the sugar loaves by sawing them 
in slices, and then cutting the slices into rectangular blocks 
by the use of a gang of small circular saws. 



PROPERTIES OF CANE SUGAR 

Cold water dissolves three times its weight of cane sugar. 

Rapid boiling changes cane sugar to barley sugar, a 
transparent, non-crystalline mass, which has, however, the 
same chemical composition as sugar. 

Experiment 121. Melt a sample of cane sugar in an iron pan 
or spoon, and examine the product, which is known as " barley 
sugar." 

If the sample is heated to 400° F., a substance called 
" caramel " results. This material is extensively used in 
confectionery, and is a harmless coloring matter for beer 
and other alcoholic liquors. 



248 



SANITARY AND APPLIED CHEMISTRY 



Experiment 122. Heat a sample of sugar to a higher tem- 
perature than in Experiment 121, and dissolve the brownish 
substance so obtained in water. Notice the taste of the solu- 
tion. When cane sugar is heated with an acid or with many 
salts and metals, the change known as " hydrolysis " takes 
place. This action is catalytic, as the " hydrolyte " does not 
enter into chemical combination with the products formed. 
This hydrolysis of cane sugar to an invert sugar can be expressed 
by the equation : C12H22O11 + H 2 = 2 C6H12O6. 

Experiment 123. To 50 cc. of a fairly strong solution of cane 
sugar add 5 cc. of hydrochloric acid, and heat the solution 
gradually to 70° C, and keep it at this temperature for a few 
minutes. By this treatment the sugar is " inverted," and the 
presence of invert sugar may be determined by the Fehling's 
test, as noted in Experiment 98. 

Experiment 124. As powdered sugar sometimes contains 
starch, a test may be made for this by boiling a sample of the 
sugar with water, cooling and adding a few drops of tincture 
of iodin. A blue coloration indicates starch. 

The following table 1 gives the average composition of 
some common grades of sugar : — 



Raw Sugaks 



Cane 
Sugar 


Glucose 


Water 


Organic 
Matter 


96.0 


1.25 


1.00 


1.25 


92.0 


2.50 


3.00 


1.75 


91.0 


2.25 


5.00 


1.10 


88.0 


2.80 


3.00 


3.50 


87.0 


5.50 


4.00 


2.25 


95.0 


— 


2.00 


1.75 


99.8 


.20 


_ 


_ 


91.0 


2.40 


5.50 


.80 


82.0 


7.50 


6.00 


2.50 


40.0 


25.00 


20.00 


10.00 



Ash 



Good centrifugal 
Poor centrifugal . . . 
Good muscovado . . 
Molasses sugar . . . 
Manila sugar .... 
Beet sugar, 1st . . . 

Refined Sugars 
Granulated or loaf sugar 
White coffee sugar . . 
Yellow sugar .... 
Barrel sirup .... 



.50 

.75 

.65 

2.70 

1.25 

1.25 



.30 
2.00 
5.00 



1 Thorp, "Outlines of Industrial Chemistry," p. 400. 



SUGARS 



249 



THE FOOD VALUE OF SUGAR 

The food value of sugar has been summarized as 
follows : * — 

1. When the organism is adapted to the digestion of 
starch and there is sufficient time for its utilization, sugar 
has no advantage over starch as a food in muscular work 
except as a preventive of fatigue. 

2. In small quantities and in not too concentrated 
form, sugar will take the place, practically speaking, weight 
for weight, of starch as a food for muscular work, barring 
the difference in energy and in time required to digest 
them, sugar having here the advantage. 

3. It furnishes the needed carbohydrate material to 
organisms that have as yet little or no power to digest 
starch. Thus milk sugar is part of the natural food of the 
infant. 

4. In times of great exertion or exhausting labor, the 
rapidity with which it is assimilated gives it certain 
advantages over starch. 

AMOUNT OF SUGAR CONSUMED 

The per capita consumption of sugar in the different 
countries for the year 1912-13 is reported to be as follows : 2 



Denmark . 
England 
United States 
Switzerland 
Sweden . . 
Netherlands 



Lb. 
98.96 
95.52 
85.40 
77.24 
57.09 
49.90 



Germany 
France . 
Norway 
Russia . 
Turkey 
Italy . 



Lb. 
48.95 
48.41 
45.83 
24.33 
19.84 
10.76 



1 Mary Hinman Abel, Farmers' Bui. 93, U. S. Dept. Agric. 

2 The World Almanac, 1915. 



250 SANITARY AND APPLIED CHEMISTRY 

MALTOSE 

Maltose (C12H22O11 + H 2 0) : this, together with dextrin, 
is made by the limited action of dilute acids or by the 
action of malt infusion on starch. This sugar probably 
does not ferment directly, but by the action of yeast its 
fermentation and conversion into dextrose go on simul- 
taneously. It is an ingredient of commercial glucose, 
and is also the sugar produced by the action of the ptyalin 
of the saliva on starch, in the process of digestion. 

The equation of changing gelatinized starch to maltose 
is as follows : — 

C18H30O15 + H2O = CeHioOs + C12H22O11. 

Starch Dextrin Maltose 

When either dextrin or maltose is heated with dilute 
acid, it is converted into dextrose. The hydrolysis in 
the case of maltose would be represented by the equa- 
tion : — 

C12H22O11 + H2O = 2 CeH^Oe. 

Maltose Dextrose 

(LACTOSE) MILK SUGAR 

Lactose (C12H22O11 + H 2 0) is made commercially by 
treating whey, a by-product in cheese making, with chalk 
and aluminum hydroxid, and after filtering off the precipi- 
tate thus produced, the filtrate is concentrated in a vacuum 
pan, and when sticks or strings are suspended in the sirup, 
the milk sugar crystallizes on them after some time. 

This sugar is not as sweet as cane sugar, but it is very 
useful in " modified milk," in making dietetic preparations, 
and as a basis for the pellets used by homeopaths. In the 
ordinary souring of milk this sugar changes to lactic acid. 
On being heated with dilute acids lactose is inverted, 
forming dextrose and galactose (see reaction under Sucrose). 



CHAPTER XVII 

THE GLUCOSE OR GRAPE SUGAR GROUP, CeHiA 

It will be noticed that under the general name " glu- 
cose " there are grouped a number of substances made by 
" hydrolysis " from starch, such as dextrose, and also sub- 
stances such as levulose, which result from the inversion 
of cane sugar. 

COMMERCIAL GLUCOSE 

When the glucose is to be made from corn, the latter is 
steeped for some time in warm water, and the softened 
grain is crushed in a " cracker " to loosen the germs. The 
coarse meal passes to the " separators/' where the germs, 
being light, float over the dam at the end of the tank. 
These germs are often used for making corn oil. The 
hulls and starchy matter are ground fine, and passed over 
" shakers " to remove the hulls. The starch suspended 
in water is now ready for the next process. 

As previously stated, when starch is boiled with dilute 
acids it is converted into a mixture of compounds of the 
grape sugar group. The commercial process of manu- 
facture is to treat the starch suspended in water, in the 
proportion of 10,000 pounds to 6 pounds, with hydro- 
chloric acid. Closed " converters " are used in this 
process, and in this case the liquid is boiled under pressure. 

When the process of conversion has been carried far 
enough and a test shows that no starch remains, the 

251 



252 SANITARY AND APPLIED CHEMISTRY 

liquor is neutralized with sodium carbonate, thus pro- 
ducing sodium chlorid, and the glucose solution is then 
decolorized by passing through bone-black filters. The 
solution is filtered through bag filters or a filter press. 
Concentration in the vacuum pan is then effected. Some 
manufacturers filter several times through bone black, and 
some use sulfur dioxid gas to bleach the product and arrest 
fermentation. 

The process of hydrolysis would in part be represented 
by the equation : — 

CeHioOs + H2O = C6H12O6. 

A number of intermediate products are formed. 

When glucose is the product desired, the conversion of 
the starch is arrested while there is still considerable of 
the uncrystallizable dextrin in the product. This gives a 
heavy sirup. If the conversion is more complete, and the 
concentration is carried further, the product is a solid 
known as " grape sugar, 17 

The composition of the two products described is as 
follows : * — 





Glucose (liquid) 


Grape Sugar (solid) 


Dextrose . . 


. . 34.3% to 36.5% 


72.0% to 99.4% 


Maltose . . . 


. . 4.6% to 19.3% 


0% to 1.8% 


Dextrin . . . 


. . 29.8% to 45.3% 


0% to 9.1% 


Water . . . 


. . 14.2% to 17.2% 


.6% to 17.5% 


Ash ... . 


. . .32% to .52% 


.3% to .75% 



Glucose mixed with molasses is frequently used in the 
manufacture of table sirups ; in beer to take the place of 
malt; in the manufacture of confectionery, of artificial 
honey, and of maple sirup, jellies, jams, vinegar, wine, etc. 
From some experiments made by the author, glucose is 
shown to be three fifths as sweet as cane sugar. 

1 Leach, "Food Inspection and Analysis," 3d ed., p. 576. 



THE GLUCOSE OR GRAPE SUGAR GROUP 253 

As to the healthfulness of glucose, the committee of the 
National Academy of Science, to whom this question was 
referred some years ago, and from whose report many of 
the facts are gathered, say that there is no evidence of ill 
effects from its use. 

The report concludes thus : " First, the manufacture of 
sugar from starch is a long-established industry ; scientifi- 
cally valuable and commercially important. 

" Second, the processes that are employed at the present 
time are unobjectionable in their character and leave the 
product uncontaminated. 

" Third, the starch sugar thus made and sent into com- 
merce is of exceptional purity and uniformity of compo- 
sition, and contains no injurious substances. 

" Fourth, having at best only two thirds the sweeten- 
ing power of cane sugar, yet starch sugar is in no way 
inferior to cane sugar in healthfulness, there being no 
evidence before the committee that maize or starch sugar, 
either in normal condition or fermented, has any deleterious 
effect upon the system even when taken in large quanti- 
ties." 

^--The glucoses, maltose, and milk sugar reduce Fehling's 
solution, but starch paste must be converted by acid, and 
cane sugar must be inverted before testing. 

Experiment 125. Use a thin starch paste prepared as in 
Experiment 92. To 200 cc. of this, add about 20 cc. of dilute 
hydrochloric acid, and boil for 15 min. Neutralize the solution 
with NaOH ; cool and test a portion, 1st, with iodin for starch ; 
2d, with Fehling's solution for dextrose. There may be some 
dextrin present, in which case a purple color will be obtained 
by iodin. 

Experiment 126. Test a sample of commercial " grape 
sugar " for starch with iodin, and for a reducing sugar by Feh- 
ling's solution.. 



254 SANITARY AND APPLIED CHEMISTRY 

Experiment 127. Macerate some raisins with water, filter 
the solution, and test a portion for grape sugar or invert sugar 
by Fehling's solution. 

Experiment 128. Crush an apple and squeeze the juice 
through a cloth, filter this, and test for the invert sugar. The 
sugar of fruit is usually invert sugar, and this, like dextrose, has 
a reducing action with Fehling's solution. 

Experiment 129. Test a dilute solution of pure honey for 
a reducing sugar by Fehling's solution. 

Experiment 130. As hydrochloric acid is now so generally 
employed in making glucose, test a dilute solution of glucose for 
a chlorid by making slightly acid with nitric acid and adding a 
few drops of silver nitrate. 

Experiment 131. Repeat the above experiment, using a 
dilute solution of honey. 

INVERT SUGAR 

Invert sugar is of importance, since it results from the 
inversion of cane sugar, and as it occurs in honey and many 
fruits. It is a mixture of equivalent proportions of dex- 
trose and levulose. It does not crystallize readily, and is 
produced in the boiling of acid fruit juices with cane sugar, 
as in the making of jellies, etc. Some authorities claim 
that invert sugar is sweeter than cane sugar. One author, 1 
however, reports as the result of his experiments that in- 
vert sugar is five sixths as sweet as cane sugar. If this is 
the case, we should expect that more sugar would be re- 
quired to sweeten canned fruit if added before cooking 
than if added afterwards. Fruit sugar, or levulose, is 
found in most fruits, and does not crystallize. Invert 
sugar is found abundantly in grapes, forming the yellowish 

1 Willard, Trans. Kan. Acad. Science, Vol. X, p. 25. 



THE GLUCOSE OR GRAPE SUGAR GROUP 255 

white granular masses in raisins. Levulose is of importance 
as a food for diabetic patients, as they utilize it more easily 
than any other form of carbohydrates. 

Experiment 132. Test some dilute cranberry or currant 
juice with Fehling's solution for fruit sugar, then boil an equal 
quantity of the juice for 15 min. with a moderate amount of cane 
sugar, and test as above. Notice by the relative quantities of 
the precipitates whether the fruit acid has " inverted " some of 
the cane sugar. 

HONEY 

During the secretion of honey in the body of the bee, 
sucrose, which is the principal constituent of the nectar, 
is mostly changed to a mixture of dextrose and levulose. 
Wax, formic acid, and flavoring substances from the flowers 
are also present. It has been estimated that to obtain a 
kilogram of honey the bee must visit from 200,000 to 
500,000 flowers. In some tropical countries certain varie- 
ties of flowers furnish a honey that is poisonous. Genuine 
honey should contain not more than 8 % of sucrose, not 
less than 25 % of water, not less than 0.25 % of ash, and 
from 60 to 75 % of reducing sugar. Whenever the dextrose 
is in excess of the levulose, it indicates adulteration with 
glucose. If ash is high, the sample is regarded with suspi- 
cion. Honeycomb consists of waxy substances which 
are probably incapable of digestion but not necessarily 
injurious. 

The following analysis shows the average composition 
of genuine honey : * — 

Sucrose (by Clerget) 5% to 7.64% 

Invert sugar 66.37% to 78.80% 

Water 12.00% to 33.00% 

Ash 03% to .50% 

1 Canadian Dept. In. Rev., Bui. 47. 



256 SANITARY AND APPLIED CHEMISTRY 

On account of the cost of honey the temptation to adul- 
teration is very great. Cane sugar and glucose are the 
common adulterants. The expedient has also been tried 
of feeding bees upon glucose, but it is said that they do not 
thrive with this treatment. It was formerly a common 
practice to put up the so-called " strained honey " in 
jars, with a piece of the comb or a dead bee, as evidence of 
its genuineness. Artificial combs are also made, but have 
not found much favor with bee keepers. As honey is 
actually richer in sugar than the malt extracts recom- 
mended for invalids, and as this sugar is nearly all in a 
form to be readily assimilated, it is considered valuable 
as a supplement to the other carbohydrates in the diet. 

Experiment 133. If honey contains dextrin, this is a good 
indication of adulteration with glucose. To test for dextrin 
add to the suspected sample 3 or 4 volumes of strong alcohol. 
In the presence of dextrin, quite a precipitate will appear, 
but in genuine honey only a slight cloudiness. 1 

Experiment 134. If honey contains any notable quantity of 
calcium sulfate, this is a pretty good indication of its adultera- 
tion with glucose. Test some diluted honey with ammonium 
hydroxid and ammonium oxalate for calcium. 

Experiment 135. To test for the genuineness of beeswax, 
add to a portion some warm sulfuric acid. Wax will be black- 
ened, while paraffin will be unchanged. 

1 Leach, loc. cit., 3d ed., p. 641. 



CHAPTER XVIII 
ROOTS, LEAVES, STALKS, ETC., USED AS FOOD 

In addition to the starch-bearing vegetable products dis- 
cussed in Chapter XIII, there are a number of roots which 
are not particularly valuable, as sources of starch, but 
which give a variety to the food supply. 

ROOTS 

The carrot belongs to the botanical order Umbelliferce, 
which includes many edible plants such as celery, parsnip, 
and parsley. Wild carrots have a very pungent odor and 
taste, but this has been modified by cultivation so as to be 
mild and agreeable. It is often necessary, however, to 
cultivate a taste for all the vegetables of this class. 
Carrots contain no true starch, but about 2.5 % of pectose, 
gum, etc., 4.5% of sugar, 0.5% of albuminoids, and 89% 
of water. When carrots are boiled they lose over 90% 
of their nutrient material. This fact suggests that to 
retain any food value at all, carrots should be cooked in a 
soup or stew. 

Parsnips have also been cultivated from the wild parsnip, 
The parsnip is somewhat more valuable as food than the 
carrot, as the former contains about 3.5 % of starch, 5 % of 
sugar, 3.7% of gum, pectose, etc., 1.5% of fat, 1.2% of 
albuminoids, and only 82% of water. It loses a large 
amount of nutrient material in boiling, 
s 257 



258 SANITARY AND APPLIED CHEMISTRY 

Turnips belong to the order of Cruciferse. They con- 
tain pectose, 3%, instead of starch, and are very low in 
albuminoids and extractives. Turnips contain 92.8% 
of water; in fact they contain more water than milk. 
They are of little value, then, except for their flavor and 
to furnish variety to the bill of fare. 

Beets are a more important food than any of those just 
mentioned, for the ordinary garden beet has been culti- 
vated so that it contains from 10 to 15 % of cane sugar, or 
about as much as the variety used for making sugar. 
Beets also contain 2.4% of pectose, and more cellulose 
than the other roots. The addition of vinegar to boiled 
beets helps to soften the cellulose, and, it is said, does not 
interfere with the digestion of other carbohydrates. After 
beets are boiled they contain only 3 % of sugar. 

LEAVES AND STALKS 

The leaves and stalks of many plants are valuable 
both for food and for relishes. One reason for this is 
on account of the large amount of mineral salts that they 
contain. Some of these would be tough and woody if 
grown under the ordinary conditions, but if they are grown 
very rapidly, in an exceedingly rich soil, or if they are 
grown partly underground, or in the shade, they are quite 
tender. Though this class of foods often contains over 
90% of water, yet their value should not be overlooked, 
for the gluten and starch which they contain are often 
in such a condition that they can be readily assimilated. 

Prominent among foods of this class should be mentioned 
the cabbage, cauliflower, and kale. The cabbage contains 
5.8% of carbohydrate, 1.8% of nitrogenous matter, and 
1.3% of mineral matter, but when cooked the percentage 



ROOTS, LEAVES, STALKS, ETC., USED AS FOOD 259 

of water is increased to 97.4 % and the other constituents 
decrease in like proportion. In general it may be said 
that the effect of cooking is to greatly diminish the amount 
of nutrients in this class of foods. The value of cabbage 
as a protection against scurvy, for those who are for a long 
time obliged to live on salted or canned meats, should not 
be overlooked. 

Cabbage is sometimes packed in salt and preserved under 
the name of " sauerkraut. " Here a kind of fermentation 
takes place and various organic acids are formed. 

When cooked with potatoes to furnish the starch, and 
pork to furnish fat and a small amount of proteins, the 
deficiencies of cabbage are to some extent made up ; really, 
however, the cabbage is but a flavoring for other food and 
adds to its bulk. 

Many other succulent vegetables are used under the 
common name of " greens," and each has its agreeable 
flavor, and may be considered of value rather as a stimu- 
lant to the appetite than as a source of nutrient material. 
Among them may be mentioned : spinach, dandelion, 
endive, watercress, beet tops, narrow-leaved dock, and 
young poke sprouts. Lettuce, which also belongs to this 
class, contains a milky juice, having mild soporific prop- 
erties, and considerable mineral salts, especially potassium 
nitrate. Asparagus, which is in much more common use 
than most of the foods mentioned, in the wild state is a 
seashore plant. It contains a peculiar crystallizable 
principle called " asparagin," C 4 H 8 N 2 03, which has diuretic 
properties. When served with toast, the combination is 
an agreeable and useful food. Celery when in its wild 
state was known as " smallage." By intense cultivation 
much of the disagreeable odor has been removed, and it has 
found great favor. On the continent of Europe the root of 



260 SANITARY AND APPLIED CHEMISTRY 

one variety is boiled, but in the United States the stalks, 
which are grown so that they are protected from too much 
light, are eaten raw for their agreeable flavor. 

Rhubarb (Rheum raphonticum) , under the name of 
" pie plant," is a useful garden production. The leaf 
stalks when cooked with sugar are used, on account of their 
flavor and the acid which they contain. As the plant is a 
slight laxative, it may be useful in cases of constipation. 
Rhubarb contains a peculiar flavoring substance and con- 
siderable acid potassium oxalate. 

Experiment 136. Express the juice from several stalks 
of rhubarb and filter it. Add to some of the clear juice a little 
solution of calcium chlorid, and notice the precipitate of calcium 
oxalate produced. 

OTHER VEGETABLE FOODS 

The onion, leek, and garlic are chiefly prized for their 
pungent volatile oil, rich in sulfur, which makes them 
useful in flavoring other food. 

The tomato, although not properly belonging to this 
class, may be here discussed. It is a native of South 
America, and was introduced into Europe in 1596. It 
has been grown and used in enormous quantities in the 
United States since about 1850. The raw tomato con- 
tains 91.9% of water, 1.3% of nitrogenous matter, 5% 
of carbohydrates, and .7 % of mineral matter, and there- 
fore is not very valuable as a nutrient, but is properly 
classed as a relish. Tomatoes owe their acidity mostly to 
the presence of malic acid. When made into "catsup" 
or " paste, " the product is sometimes adulterated, and 
various preservatives are also used. 



ROOTS, LEAVES, STALKS, ETC., USED AS FOOD 261 

ALGJS, LICHENS, AND FUNGI USED AS FOOD 

The most important of the algse is the Irish or Car- 
rageen moss. When dried, as usually prepared for market, 
it contains 9.4% of nitrogenous matter and 55.4% of a 
vegetable mucilage. Its value as a nutrient is not fully- 
understood. 

Iceland moss is darker in color than Irish moss and con- 
tains 8.7 % of proteins and 70 % of a lichen starch, which is 
unaffected by digestion, and probably does not form 
glycogen. It has not been proved that it has any value 
as food. 

The edible fungi are popularly classed as mushrooms 
and the poisonous ones as toadstools, but this is not a 
scientific classification. Mushrooms are employed not 
only for flavoring, but also as food. They are grown in 
large quantities in Europe in caves and cellars, in an ex- 
ceedingly rich soil. They contain from 1.19 to 6.1% of 
proteins, and from 1.2 to 6 % of carbohydrates, but starch 
is not present among the carbohydrates. Although the 
analysis shows considerable nitrogen, much of this is in 
such a combination that it is not available for nutrition. 
It is said that mushrooms are not easily digested, on ac- 
count of the large amount of cellulose which they contain. 
Some authorities claim that their use as a nutritious food 
should be encouraged, while others believe them to be 
simply a rather expensive flavoring material. The varie- 
ties known as truffles and morels are quite popular in 
England and on the Continent. 

Unfortunately several varieties of mushrooms are ex- 
tremely poisonous. In some cases the symptoms of the 
poisoning do not appear till after more than twenty-four 
hours. The poisonous substance is an alkaloid, a gluco- 



262 SANITARY AND APPLIED CHEMISTRY 

side, or a toxalbumin, and is of different composition in the 
different varieties. 1 As the taste for mushrooms is being 
cultivated, a larger number of persons are becoming ac- 
quainted with the characteristics of edible mushrooms, 
and in some countries special pains is taken to educate 
the common people to recognize the non-poisonous varieties. 
There seems to be no safe rule, however, by which we can 
distinguish between the poisonous and edible varieties, 
and it is hazardous for persons not well acquainted with 
fungi to attempt to do this. 2 

1 See U. S. Dept. Agric, Div. Microscopy, Food Products, 1893-1894. 
2 " Source, Chemistry and Use of Food Products," Bailey, p. 296. 



CHAPTER XIX 
THE COMPOSITION AND FOOD VALUE OF FRUITS 

The term " fruit ," in the restricted sense, includes the 
pulpy substance inclosing the seeds of various plants, and 
especially those which are edible in the raw state. 

Fruits are essential to the distribution of plants, and 
have been utilized by man as food, as an agreeable luxury, 
and an aid to digestion. In general it may be stated that 
the seed is surrounded by some sweet, or edible envelope, 
to attract birds, insects, and quadrupeds, and in this way 
insure the scattering of the seed over a wider extent of 
territory. 

The seed proper is surrounded by a fleshy portion known 
as the pericarp. A green fruit does not differ very much 
from the leaf in composition, but in the process of ripening, 
under the influence of sunlight, the fruit undergoes a 
remarkable change in color, texture, composition, and 
flavor. During the change it ceases to act on air like a 
leaf, but begins to absorb oxygen, and give out carbon 
dioxid gas. 

As the process of ripening goes on, both the invert sugar 
and the sucrose increase and the starch and free acid de- 
crease. After the disappearance of the starch the sucrose 
disappears quite rapidly on account of its change to invert 
sugar. Malic acid appears to decrease, but this phenome- 
non is largely due to the fact that it is formed in the 
early life history of the fruit, and is diluted by its growth. 

263 



264 



SANITARY AND APPLIED CHEMISTRY 



These changes are very well illustrated by the examina- 
tion of the analyses of Ben Davis apples, which were 
made at different stages of their growth. 1 



Date of Analyses 


Total 
Solids 


Acid as 
Malic 


Starch 


Sucrose 


Invert 

Sugar 


June 16 . . . 


13.63 


1.64 


2.23 


.49 


2.35 


June 30 






13.37 


1.27 


3.03 


.67 


3.04 


July 13 






13.58 





3.72 


1.21 


5.09 


July 28 






15.71 


.89 


3.67 


1.13 


4.52 


Aug. 18 






14.92 


.78 


3.16 


1.46 


4.36 


Sept. 24 






15.05 


.52 


2.40 


2.59 


4.83 


Oct. 15 






14.86 


.52 


1.46 


3.13 


5.30 


Oct. 23 






14.82 


— ■ — 


.94 


3.92 


5.53 


Oct. 30 






14.68 


.43 


.38 


3.87 


5.84 


Nov. 5 






15.73 


.41 


— ■ — 


3.71 


5.83 



It is supposed, while ripening, that the insoluble pectose 
changes into pectin and secondary substances of a gelati- 
nous nature. The tannin that made the fruit astringent 
also disappears. As the fruit becomes overripe, some of 
the sugar and acid is oxidized or otherwise changed, and 
the fruit loses its agreeable flavor. On cold storage this 
latter change is deferred by the low temperature, but a 
very short exposure to air, at ordinary temperature, 
causes the fruit not only to appear overripe but to decay 
quickly. During the process of decay, which is assisted 
by fermentation, carbon dioxid and alcohol are at first 
formed from the sugar, and later the alcohol is oxidized 
to acetic acid, and finally in the decayed fruit the seed is 
set free, ready to start a new plant. 

Fruits owe their agreeable taste to the right proportion 

of the constituents mentioned in the table on p. 265, and 

1 Bigelow, Gore, and Howard, U. S. Dept. Agric, Bu. Chem., Bui. 
94, p. 46. 



THE COMPOSITION AND FOOD VALUE OF FRUITS 265 

to the compound ethers and essential oils that may be 
present. These flavoring substances are many of them 
present in such small quantity that they are not mentioned 
in the analysis. 

The composition of some of the most important fruits, 
as purchased, and including the refuse, is given by At- 
water and Bryant, 1 as follows : — 



FRUITS 





























*< H 








BO 


« 


g 




A 








P 


4J 


P 




<J £ 


Q 






fe 


O 


H 


£ w 


P 


W 




1 


£ 


« 


< 


O o 


« 


02 




tf 


fc 


fR 


Eh fl 


o 


< 


Apples 


25.0 


63.3 


.3 


.3 


10.8 


_ 


.3 


Blackberries 








— 


86.3 


1.3 


1.0 


10.9 


2.5 


.5 


Cherries . 








— 


76.8 


.9 


.8 


15.9 


— 


.6 


Cranberries 








— 


88.9 


.4 


.6 


9.9 


1.5 


.2 


Currants . 








— 


85.0 


1.5 


— 


12.8 


— 


.7 


Figs, fresh 








— 


79.1 


1.5 


— 


18.8 


— 


.6 


Grapes . . 








25.0 


58.0 


1.0 


1.2 


14.4 


— 


.4 


Muskmelon 








50.0 


44.8 


.3 


— 


4.6 


— 


.3 


Oranges 








27.0 


27.0 


.6 


.1 


8.5 


— 


.4 


Pears . . 








10.0 


76.0 


.5 


.4 


12.7 


— 


.4 


Plums . . 








50.0 


74.5 


.9 


— 


19.1 


— 


.5 


Raspberries 








— 


85.8 


1.0 


— 


12.6 


2.9 


.6 


Strawberries 








22. 


85.9 


.9 


.6 


7.0 


— 


.6 


Watermelon 2 






59.4 


92.4 


.4 


.2 


6.7 


— 


.3 



Some fruits that seem to "melt in the mouth" really do 
contain considerable soluble matter. It is a well-known 
fact that sugar disguises acids, and that an agreeable 
taste in preserved fruits is often due to a judicious mix- 
ture of the acid and the sweet. The most important 
nutritive material in fruits is in the carbohydrate group : 
of course there are some special fruits like the olive and 
the avocado which contain large quantities of fats. Al- 

1 U. S. Dept. Agric, Office of Exp. Sta., Bui. 28. 2 Edible portion. 



266 SANITARY AND APPLIED CHEMISTRY 

though starch is found at certain stages of growth, sugar 
is the most abundant of the carbohydrates. This is 
usually invert sugar, but apricots, pineapples, and apples 
contain also cane sugar. This fact has an important 
bearing on the dietetic use of fruits, as invert sugar is, 
in some diseases, as diabetes, more easily assimilated than 
cane sugar. 1 

The pectous bodies referred to above are not very well 
understood, but are regarded as resulting from the combi- 
nation of several simpler carbohydrates. 2 The insoluble 
galacto-araban is supposed to give the property of hard- 
ness to unripe fruits and vegetables, and is the basis for 
the making of jelly. The statement has been made that 
as the fruit becomes riper the pectose is changed by the 
action of acids into pectin, a vegetable jelly, which causes 
the juice after boiling to gelatinize when cooled. This 
may be noticed in the juice that exudes in the baking of 
apples. It is supposed that by too long boiling these 
pectous compounds are concentrated into a more soluble 
modification, and, if this is true, it may explain the fact 
that sometimes fruit juices that have been boiled for a 
long time become thick and viscid, but do not form a true 
jelly. A partially ripe fruit is better adapted to making 
a jelly than one that is fully ripe. 

From what has been said it is evident that pectin bodies 
are substances in a " colloid " condition very widely dis- 
tributed in plant tissues. They occur both in soluble and 
insoluble forms. In the study of these bodies " the most 
important problem appears to be the quantitative deter- 
mination of the pectin bodies occurring in a given tissue, 
because such a method could be used to determine the 

x See also, "Source, Chemistry and Use of Food Products," Bailey. 
2 Univ. 111. Bui., Vol. 9, No. 36. 



THE COMPOSITION AND FOOD VALUE OF FRUITS 267 

function of the material in plants : whether, for example, 
it is a reserve material, a by-product, is used for structural 
purposes, or has all three functions or two of them; 
whether the nature of the pectin body changes with the 
growth of the tissue, or possesses a practically constant 
composition; whether the pectin bodies obtained from 
different sources are identical, are mixtures of the same 
substances (such as araban and galactan) in varying pro- 
portions, or are inherently different/' l 

Experiment 137. To the filtered juice of a ripe apple add 
an equal bulk of alcohol, and a gelatinous mass consisting largely 
of pectin will be precipitated. Dry the product, and it will 
be found that the powder thus obtained is soluble in cold water. 

Experiment 138. Stew a handful of cranberries, filter the 
juice, add a little sugar, and allow it to stand until cold, when 
an abundant jelly is obtained. 

Experiment 139. Test some green fruit, a persimmon 
or banana, for tannin by extracting the juice, filtering, and 
adding a small quantity of ferric chlorid. The production of a 
black, or greenish black, color indicates tannin. 

FRUIT ACIDS 

The acidity of fruits is due to the presence of the free 
acids, malic, citric, tartaric, or racemic, or their acid salts. 
They not only have an agreeable acid taste, and serve 
as appetizers, but when oxidized in the body are converted 
into the corresponding carbonates, and these help to ren- 
der the blood more alkaline and the urine less acid. 

Malic acid (H 2 C 4 H 4 05) is found in many acid fruits, as 
cherries, apples, raspberries, gooseberries, rhubarb, unripe 
mountain ash berries, etc. 

1 Bigelow, Gore, and Howard, U. S. Dept. Agric, Bu. Chem., Bui. 94, 
p. 86. 



268 SANITARY AND APPLIED CHEMISTRY 

Experiment 140. Add to a solution of malic acid, calcium 
chlorid, ammonium chlorid, and ammonium hydroxid in excess. 
There should be no precipitate, but upon adding to this 3 volumes 
of alcohol, calcium malate (CaC 4 H 4 05, 3 H 2 0) should separate 
out as a precipitate. 

Experiment 141. Since the acid potassium malate exists in 
the stalks of the common rhubarb, the juice that is expressed 
from this may be filtered and tested for malic acid by the test 
described in Experiment 140. 

Citric acid, H3C6H5O7, occurs in the juice of lemons, cur- 
rants, unripe tomatoes, gooseberries, etc. It is made on 
a large scale from lime or lemon juice, by saturating the 
juice with chalk ; the precipitate of calcium citrate is 
decomposed by an equivalent quantity of sulfuric acid 
and filtered from the calcium sulfate. Evaporate the fil- 
trate and crystallize out most of the calcium sulfate, and 
from the mother liquor allow the citric acid to crystallize. 

Experiment 142. Make citric acid from the juice of at 
least two lemons, as above described. 

Experiment 143. Add a moderate quantity of calcium 
chlorid to a concentrated solution of citric acid, and then add 
sodium hydroxid till the solution is nearly neutral. Calcium 
citrate, Ca3(C 6 H 5 07)2, will be formed. 

Experiment 144. Try the above test with a concentrated 
and filtered sample of lemon juice, and note the formation of 
the precipitate of calcium citrate. 

Tartaric acid (H2C4H4O6) is found in many f nuts, particu- 
larly ripe grapes, as acid potassium tartrate (KHC4H4O6). 
When the " must " ferments, the " cream of tartar " precipi- 
tates as the alcohol increases, and this precipitate is known 
in the market by the name of "argol," or crude tartar. 



THE COMPOSITION AND FOOD VALUE OF FRUITS 269 

It is frequently much contaminated with calcium sulfate, 
which is used in " plastering " the wine. To make tartaric 
acid from this, the solution of the argols is treated with 
milk of lime to form the calcium tartrate, and the latter 
salt is suspended in water and treated with an equivalent 
of sulfuric acid, the calcium sulfate so formed is filtered 
off, and the tartaric acid is obtained in crystals by con- 
centration of the filtrate. 

Experiment 145. Add to a concentrated solution of tar- 
taric acid a concentrated solution of potassium chlorid, when 
a precipitate of acid potassium tartrate will be formed on shak- 
ing and allowing to stand at ordinary temperature. The test 
is more delicate if the solution is nearly neutralized with sodium 
carbonate before the potassium chlorid is added. 

Experiment 146. Make a similar experiment with filtered 
grape juice, which may conveniently be obtained from canned 
grapes. A more delicate test is made by adding to 100 cc. of 
the fruit juice a few drops of strong acetic acid, a few drops of 
a concentrated potassium acetate solution, and 15 g. of pure, 
finely ground potassium chlorid; dissolve the latter salt by 
shaking and add 20 % of 95 % alcohol. Stir and shake vigorously 
to assist in the crystallization of the acid potassium tartrate. 

COOKING FRUITS 

Cooking improves many fruits by softening the cellu- 
lose and converting the gums and allied bodies into a ge- 
latinous form. Sucrose is inverted and pectin bodies con- 
verted into soluble forms. If there is starch remaining, 
this is made more digestible by cooking. There are 
many fruits that in the raw state are not suitable to use 
as food for persons with dyspeptic tendencies. They 
are, however, very satisfactory and useful when suitably 
cooked. Apples, pears, quinces, and cranberries belong 



270 SANITARY AND APPLIED CHEMISTRY 

to this class. It should also be noted that a jelly made 
from a fruit juice is usually much more acceptable to 
an invalid and less irritating in its action than the raw 
fruit or the jam. This is especially true of raspberries, 
blackberries, and currants, on account of the numerous 
fine seeds that are present in the jam. 

Cultivation has changed the character of many fruits, 
and has much improved their flavor, so that many lus- 
cious fruits have been developed from disagreeable, or, 
to say the least, very medium stock. 

JAMS AND JELLIES AND THEIR ADULTERATION^ 

Although a few years ago preserved fruit products were 
all prepared by the housewife, at the present time much of 
this work is turned over to the manufacturer, and he has 
the opportunity and often the incentive to falsify the 
material, and to give it a fictitious value in color, odor, 
sweetness, flavor, and preservative qualities. Much work 
has been done on this subject by the United States Depart- 
ment of Agriculture and at State Experiment Stations. 
The presence in these products of anything in addition to 
the fruit and cane sugar should be regarded as an adultera- 
tion. If they are made up with foreign materials they 
should, in the interest of the purchaser, at least be labeled 
" compound.'' 

The substitute for jam and jelly, which is sold at say 
10 j£ per half-pound jar, is often made of apple juice or 
" trimmings " from canning factories, and glucose, colored 
with coal-tar dyes to imitate any natural product, as 
strawberry, currant, etc., and occasionally flavored with 
an artificial fruit essence. 

As it is difficult to secure sufficient stiffness in an apple- 



THE COMPOSITION AND FOOD VALUE OF FRUITS 271 

jelly stock with glucose, a little citric, tartaric, or phos- 
phoric acid is added to cause the mass to gelatinize. 1 

Foreign seeds, like that of the clover, are sometimes used. 
Although a sample of jam may contain the seeds of the 
genuine fruit, and so appear to be genuine, yet the fruit 
may be first used to make a high grade of jelly, and 
the residue may be afterwards worked up into a cheap 
jam. 

Experiment 147. The test for a coal tar dye in jelly may 
be made as follows : Strips of a fine woolen cloth, such as " nun's 
veiling/ ' are boiled and then thoroughly washed. One of these 
strips is then boiled for about 15 min. in a diluted, filtered solu- 
tion of the jam or jelly, to which a little potassium bisulfate has 
been added. The wool is then taken out and boiled with water 
containing a very little soap, and if it has been colored at all 
with the dye it is digested in another beaker with dilute am- 
monia, which will dissolve the colors fixed in the acid bath. 
Take out the fabric, slightly acidify the solution, and boil with 
a new piece of the fabric. This second dyeing will fix the coal- 
tar colors, on the goods but will not fix the natural fruit colors. 
There are a few rather uncommon coloring matters, made by 
chemical methods of manufacture from vegetable substances 
like cudbear and archil, which are not to be distinguished from 
aniline dyes by any method of dyeing. 2 

Experiment 148. To detect starch in jelly, heat an aqueous 
solution of the sample nearly to the boiling point and decolorize 
by the addition of several cubic centimeters of dilute sulfuric 
acid and afterwards a small quantity of potassium permanganate. 
Cool the solution, filter if necessary, and test for starch by the 
iodine reagent as usual. Very little starch is normally present 
in apple juice, but if the jelly is made from apple parings and 
trimmings a little starch is frequently present. 3 

1 Leach, " Food Inspection and Analysis," 3d ed., p. 934. 

2 Winton, J. Am. Chem. Soc, 22, 1900, p. 582. 

3 U. S. Dept. Agric, Bu. Chem., Bui. 65. 



272 SANITARY AND APPLIED CHEMISTRY 



FRUIT SIRUPS; FLAVORING EXTRACTS 

The fruit sirups upon the market may be made from 
genuine fruit, sterilized by heating, and put up practically 
like canned fruit, or they may be entirely artificial, like 
some of the jellies just mentioned. 



VANILLA EXTRACT 

Among the flavoring extracts, that of vanilla and lemon 
are most extensively used. Practically, only a small pro- 
portion of the vanilla extract on the market is made wholly 
from the vanilla bean, as this is very expensive. Most of 
the agreeable flavor of vanilla extract is due to the presence 
of a body called vanillin, C 8 H 8 3 . Many of the cheaper 
so-called vanilla extracts on the market are made by the 
use of the Tonka bean, which contains the active principal 
coumarin, C 9 H 6 2 . Some manufacturers claim that the 
quality of the extract is improved rather than otherwise by 
the use of the Tonka bean. 

Much of the ordinary " compound " vanilla extract is 
made by the use of the artificial vanillin, and artificial 
coumarin, with some coloring matter and sugar, added to a 
weak alcoholic tincture of the Tonka bean. 1 

Experiment 149. Place some extract of vanilla in an evap- 
orating dish on a water bath and evaporate off half of the 
liquid. Add cold water to make up to the original volume. 
By this treatment the alcohol will be driven off, and in the watery 
solution that is left the substances in true vanilla are nearly 
insoluble, so the liquid will be cloudy and of a dirty brownish 
color. The artificial extract, on the other hand, will be bright 
and clear. 

i Lab. Inl. Rev. Dept. Can., Buls. 89 and 114. 



THE COMPOSITION AND FOOD VALUE OF FRUITS 273 

Experiment 150. In a test tube add a little of a solution of 
sugar of lead to some of the extract of vanilla. The true vanilla 
extract will give an abundant yellowish brown precipitate and 
a pale yellowish liquid. Upon the artificial extract the lead 
solution has but little effect, and there is only a slight discolora- 
tion. Another test is to notice the character and color of the 
foam produced on shaking some of the artificial vanilla extract. 
The bubbles will retain their bright caramel color till the last 
ones have disappeared, while, if the extract is genuine, the bubbles 
are much fighter in color. 

LEMON EXTRACT 

Extract of lemon should contain, according to the U. S. 
Pharmacopoeia, 5% of oil of lemon, and to keep this in 
solution will require alcohol of 80 % strength by volume. 
Much of the extract of lemon on the market contains 
only a trace of the oil, and less than 40% of alcohol. A 
sample of alcohol so dilute as this will dissolve only a very 
small quantity of the oil, although there may be enough to 
give the extract a slight taste and odor. Such extracts 
are usually colored yellow by the use of coal-tar dyes. 1 

Experiment 151. To 50 cc. of water add 10 cc. of the 
extract of lemon to be tested. If the solution becomes milky, 
on account of the precipitation of the oil of lemon, it is of good 
quality, but if it remains clear only traces of the oil are present. 

ARTIFICIAL FRUIT ESSENCES 

Most of the artificial fruit essences, such as that of straw- 
berry, banana, raspberry, apple, and pineapple, are made 
by ingeniously combining various compound ethers, 
organic acids, and essential oils. These are usually colored 
with aniline colors, and may be sweetened by the use of 
glucose or saccharin. 1 

1 U. S. Dept. Agric, Bu. Chem., Bui. 65. 
T 



CHAPTER XX 
EDIBLE FATS AND OILS 

The fats used in the manufacture of soap have already 
been discussed, but the importance of certain fats and oils 
in food products warrants some further attention to them 
in this connection. The facility with which a fat saponifies 
(see p. 129) is of great importance in the process of diges- 
tion. The fats are insoluble in water, but readily 
soluble in ether, chloroform, oil of turpentine, and similar 
solvents. 

Like starch and sugar, the fats do not directly form 
muscular tissue, but they have 2| times the power to 
maintain the heat and activity of the body that the 
carbohydrates possess. There seems to be little difference 
whether the fat comes from a vegetable or an animal 
source. 

The amount of fat existing in some food products is as 
follows : — 

From vegetable sources — 



Almonds . . . 
Peanuts . . . . 
Olives (pulp) . 
Cacao .... 
Cocoanut 


Per Cent 

. . 54.0 Sunflower seed . . 

. . 41.6 Oatmeal 

. . 56.4 Indian corn (white) . 
. . 44.0 Wheat bran . . . 
. . 68.7 Peas 


Per Gent 

. 20.5 
. 6.0 
. 4.2 
. 4.0 
2.5 


Cotton seed . . 


. . 20.1 Wheat flour . . . 


. 1.0 



274 



EDIBLE FATS AND OILS 275 

From animal sources — 

Per Gent Per Gent 

Butter 84.4 Poultry 16.3 

Bacon 65.0 Mackerel 13.0 

Mutton chop .... 35.0 Eggs (whole) .... 11.0 

Cheese 30.0 Cow's milk 4.0 

When fat is deposited in the body beneath the skin, it 
keeps in the warmth of the body. The fat, wherever depos- 
ited, may be reabsorbed into the blood, and thus keep up 
the animal heat for a long period even when food is not 
taken. This is the case with animals which hibernate for 
several months. 

The demand for some of the oils has been constantly 
increasing. Previous to 1870 it was quite a problem to the 
cotton planters how they should dispose of their cotton 
seed, while to-day the oil extracted from it finds numerous 
uses. A large quantity is exported to Europe, where it 
is used in the manufacture of soaps and butterine, and oc- 
casionally as an adulterant for olive oil. Cottonseed oil is 
used in the United States in canning factories in the pres- 
ervation of fish, in the manufacture of " cottolene," 
butterine, and soap, and for the preparation of salad 
dressing. The cottonseed-oil product of a single year 
was 93,325,729 gal. and only 53% of the possible product 
was produced. 

The oil of the cocoanut is also exceedingly valuable, 
both for cooking and in the manufacture of soap. It is 
imported from various tropical countries, especially Ceylon 
and the East Indies. Unfortunately, the oil soon be- 
comes rancid, and therefore it is more extensively used for 
food in the countries where it can be freshly obtained than 
elsewhere. 



276 SANITARY AND APPLIED CHEMISTRY 

LARD 

The " rendered " fat of the hog has the general name of 
lard, but there are several different grades made at the 
packing-house. The lowest grade, known as " steam-ren- 
dered " lard, or " prime steam lard," is extracted from the, 
stock by admitting steam to the tank under a pressure of 
40 to 50 lb. The object of cooking lard or suet material 
is to break the membranous cells, thus allowing the fat to 
escape, and to heat the small quantity of the nitrogenous 
portion that may remain in the finished product so that it 
will not readily decompose. 

A " refined lard " is sometimes made from the " prime 
steam lard " by heating it in a tank to 170° F. and blowing 
in air for some time to remove moisture. It is then 
bleached at a temperature of 150° to 165° F., by agitation 
with Fuller's earth, and filtered through a filter press. 
The final operation in the manufacture consists of cooling 
rapidly, either by agitating in a tank surrounded by cold 
water, or by running the lard on to a large roll, which is 
filled with ice-cold brine, and which slowly revolves. 

Kettle " rendered " lard is that which is made in kettles 
heated externally, and corresponds to ordinary household 
lard. The best grade of " leaf lard " belongs to this class. 
The material, which has been thoroughly washed, is 
heated at as low a temperature as possible to secure the 
result, in steam-jacketed kettles, and when fully rendered 
is drawn off into a settling tank, before being filled into 
packages for shipping. The " scrap " remains in the 
bottom of the rendering kettle, and is worked over again. 

The method of making " neutral lard/' which is made 
from leaf lard principally, is described under oleomargarine 
(Chapter XXIII). As it is not fully heated, its keeping 



EDIBLE FATS AND OILS 



277 



qualities are not good, and it must be kept in cold 
storage. 

Lards are sometimes " stiffened " so that they will not 
melt so readily in a warm climate, and if this is done by 
the addition of lard stearin it is not considered an adultera- 
tion, but the use of the oleostearin from beef should be 
considered an adulteration. 

" COMPOUND LARD," " COTTOLENE," " COTTOSUET " 

There are a number of products on the market which do 
not pretend to be lard, but are made to use for the same 
purposes, and can be sold at a lower price. Different mix- 
tures of fats are used for the trade of different countries, 
and for summer and winter trade. The chief materials 
used are: cottonseed oil, oleostearin, tallow, and some- 
times lard. These materials are each carefully bleached 
before being mixed. 

THE COMPOSITION AND FOOD VALUE OF NUTS 

Within the last few years many nut preparations have 
appeared on the market, so that their use as food should 
be no longer ignored. Nuts have a much higher nutritive 
value than fruits, as can be readily seen from their com- 
position. 1 



Nuts as 
Purchased 


Refuse 


Water 


Pro- 
tein 


Fat 


Total 
Carbo- 
hydrates 


Ash 


Almonds . . 


45.0 


2.7 


11.5 


30.2 


9.5 


1.1 


Chestnuts 


16.0 


37.8 


5.2 


4.5 


35.4 


1.1 


Cocoanuts . 


48.8 


7.2 


2.9 


25.9 


14.3 


.9 


Hickory nuts 


62.2 


1.4 


5.8 


25.5 


4.3 


.8 


Pecans . . 


53.2 


1.4 


5.2 


33.3 


6.2 


.7 


Peanuts . . 


24.5 


6.9 


19.5 


29.1 


18.5 


1.5 



i U. S. Dept. Agric, Office Exp. Sta., Bui. 28. 



278 SANITARY AND APPLIED CHEMISTRY 

Since they contain a large amount of fat, various nut 
preparations are used as substitutes for butter. On ac- 
count of the fact that nuts are not readily digested in the 
stomach, the attempt has been made, and with consider- 
able success, to improve the product, by crushing and 
removing the excess of oil and cellulose. 

Chestnuts, 1 which are used very extensively as food by 
the peasants of southern Europe, have been mentioned 
under the starchy foods. 

In the almond-producing countries the nut is eaten 
both green and dry. When the skin has been softened by 
soaking for some time in warm water, it may be removed 
and the nuts are said to be " blanched. " 

It is interesting to note that there are two kinds of 
almonds, the sweet and the bitter, both of which contain 
a peculiar ferment called " emulsin." The bitter almond 
contains, in addition to this, an interesting " glucoside " 
known as amygdalin, C20H27NO11 + 3 H 2 0. This, in the 
presence of water, is broken up by the emulsion into 
glucose, benzoic aldehyde, and hydrocyanic acid, HCN. 
It is on account of the formation of this latter compound 
that bitter almonds are poisonous. Amygdalin is also 
obtained from the seeds of plums, peaches, cherries, 
apples, etc. 

The cocoanut is probably the most important of any 
staple nut products. As the edible part or meat contains 
about 50 % of oil, the abundance of nutrient material can 
be readily appreciated. Each tree yields from 80 to 100 
nuts a year, and will continue to bear for at least two 
generations. The importance of the oil in various in- 
dustries, such as that of soap and candle making, should 
not be overlooked. 

1 " Source, Chemistry and Use of Food Products," Bailey, p. 333. 



EDIBLE FATS AND OILS 279 

The peanut, although not properly a nut, as it belongs 
to the leguminous family, since the edible portion contains 
about 38 % of oil, may properly be considered here. As it 
contains 25% of albuminoids, and considerable starch, 
it very deservedly is coming into more general use 
both as a food for man and for cattle. Three hundred 
million pounds of peanuts are grown annually for use in the 
United States. The principal peanut-producing states are 
Virginia and North Carolina. As sweet almonds and 
peanuts resemble meat in their high protein and fat 
content, they may be used to a certain extent to take the 
place of meat. 

Experiment 152. To show the relative amount of stearin 
in different oils, place test tubes containing samples of cottonseed 
oil, olive oil, corn oil, peanut oil, etc., in a beaker containing melt- 
ing ice. After some time observe the precipitate of stearin 
in each sample. 



CHAPTER XXI 
NITROGENOUS FOODS 

In Chapter XII it is stated that foods are divided into 
two general classes, carbohydrate and nitrogenous, and 
that the carbohydrate foods contain sugars, starches, 
dextrins, and fats, and also that there are many foods 
that contain both classes of nutritive materials. The 
relation between these different foods may be seen by com- 
paring the composition of the cereals and the leguminous 
foods. 

If, however, we wish to make use of a concentrated nitrog- 
enous food, it is possible to utilize the system of some 
animal that subsists on vegetable food, and so we use as 
nitrogenous foods, beef, mutton, lean pork, fish, oysters, 
poultry, game, milk and its products, and eggs. Of all 
these, beef may be regarded as the most typical nitroge- 
nous food, and it is, no doubt, the most valuable meat for 
all purposes. 

Animal foods leave comparatively little residue, as they 
are practically completely digested; they form, then, a 
concentrated food. Not only are the animal foods of 
agreeable flavor, but they contain mineral salts, which are 
of great value in the nutrition of the body, 

" Since, in some way as yet unknown to us, nitrogen is 
essential to living matter, such substances as contain this 
element in an available form are of first importance. 
Some, as albumen, are so closely allied to human proto- 
plasm that they probably need only to be dissolved to be at 

280 



NITROGENOUS FOODS 281 

once assimilated. Others, as gluten and similar vegetable 
products, undergo a still greater change ; while still 
others, as gelatin, have a less profound but marked effect 
in protecting the tissues from waste. Still other nitroge- 
nous substances, as the alkaloids, seem to affect the nerve 
tissue for good or ill. The enzymes, ' ferments ' in part, 
of the older nomenclature, are also highly nitrogenous 
substances, present in some form in nearly all the foodstuffs 
of natural origin. The nearer the composition of the food 
approaches to the protoplasmic protein, presumably the 
greater its food value, since each cleavage, each hydrolysis, 
each step in the breaking down of the highly complex 
molecule, consisting of hundreds of atoms, is supposed 
to liberate stored energy. Therefore it is not a matter 
of indifference in what form this essential is taken. " 1 

CLASSIFICATION OF NITROGENOUS SUBSTANCES 

The following is a convenient classification of nitroge- 
nous bodies that occur in food. 2 

I. Proteins. These bodies contain nitrogen, oxygen, 
hydrogen, carbon, and sulfur, and are capable of being 
converted, in the body, into proteoses and peptones. 
They may be present in either animal or vegetable food. 
Under this general head the following divisions are 
made : — 

1. Albumins, which occur in eggs, milk, cereals, etc. 

2. Globulins, which occur in serum, in blood, as myosin 
in meat, as vitellin in egg yolk, and as vegetable vitellin in 
cereals and in peas, beans, etc. 

3. Albuminates, occurring in casein of milk, in peas and 
beans, and in almonds. 

1 Richards and Woodman, "Air, Water, and Food," p. 142. 

2 Leach, "Food Inspection and Analysis," p. 40. 



282 SANITARY AND APPLIED CHEMISTRY 

4. Proteoses, which occur in sour milk, ripened cheese, 
and wheat flour. 

5. Peptones, which are found in meat. 

6. Insoluble proteins, such as fibrin and myosin, in ani- 
mal foods and gluten in wheat. 

II. Albuminoids. These are much like the proteins, 
and may be divided into — 

1. Collagen, which composes the fibers of connective 
tissues. 

2. Gelatin, which is made by boiling bones. 

3. Mucin, which is found in meat and also in mucus. 

4. Nuclein, which occurs in the nuclei of cells in the 
egg yolk and milk. 

5. Chondrin, a substance that may be obtained from 
cartilage by long boiling. 

6. Elastin, which forms the elastic fibers of connective 
tissue. 

III. Amides, amido-acids, and allied products in- 
clude cholin (C3H15NO3), betain (C5H11NO2), and asparagin 
(C4H 8 N 2 3 ). 

IV. Alkaloidal substances, such as those occurring in 
the beverages, tea, coffee, cocoa, and kola. 

V. Nitrogen, as nitrates. 

VI. Nitrogen, as ammonia. 

VII. Lecithin (C44H90NPO9), which is found in egg 
yolk, cereals, and legumes. 

" The function of the albuminous substances is probably 
threefold, as they contribute to the formation and repair 
of the tissues and fluids of the body, and in a special 
manner of the nitrogenous tissues; they regulate the 
absorption and utilization of oxygen, and so play an im- 
portant part in the chemistry of nutrition; and under 
special conditions they may also contribute to the forma- 



NITROGENOUS FOODS 283 

tion of fat, and to the development of muscular and ner- 
vous energy, and to the production of heat." * 

The structure of lean meat may be compared to bundles 
of tubes or fibers filled with rich nitrogenous juices. 
These fibers are soft and tender in the young animal, but 
with age the muscles become toughened and more firmly 
bound together. This muscular tissue is divided into two 
classes : the voluntary, or striated muscles, like those of the 
shoulder ; and the involuntary, or non-striated muscles, 
like those of the heart. The latter are not considered so 
valuable for food. The substance of the connective tissue 
consists chiefly of the albuminoids, elastin, and collagen, 
the latter being a substance which is changed by boiling 
with water or treatment with acids into gelatin. The 
proteins of the meat juice consist chiefly of the globulin 
myosin, muscle albumen, and muscle pigment. 

In the living muscle, while there are no peptones, the 
ferment pepsin is present, and after death, by the action 
of the pepsin in the presence of lactic acid, a portion of the 
normal protein of the muscle seems to undergo a kind of 
digestion, so that in the meat traces of both peptones and 
proteoses are found. Ordinarily these latter bodies are 
the result of some digestive action on higher proteins. 
We have also present in the meat, creatin, xanthin, etc., 
which are known as flesh bases. It is evident that the 
nitrogenous bodies constitute the bulk of lean meat, while 
the carbohydrates are almost entirely lacking. It should 
be noted that the different " cuts " of meat have entirely 
different food values. It is not possible by a chemical 
analysis alone to distinguish between the meat from differ- 
ent animals. 

Since myosin has the property of clotting after death, 

1 1. B. Yeo, "Food in Health and Disease," p. 13. 



284 



SANITARY AND APPLIED CHEMISTRY 



the meat undergoes the process of muscle stiffening or 
rigor mortis. If the meat is allowed to stand until this con- 
dition has passed off, on account of the resolution of a part 
of the myosin, and the partial digestion from the pepsin 
present, it becomes tender again. This process should not 
be allowed to go too far, or the meat will become " high " 
and have a disagreeable odor and flavor. 

The character of the extractives very much modifies the 
flavor of the meat, and if these extractives are removed 
by prolonged boiling or digestion with water, the meat has 
very little taste. The following analyses show the propor- 
tion of the important ingredients in one kind of meat : — 

EFFECT OF COOKING 



Lean Beef 1 
Protein . . . 
Gelatin (Collagen 
Fat .... 
Extractives . . 
Ash ... . 
Water . . . 



Raw Beef 2 Roasted Beef 2 

18.36 Water . . 70.88 55.39 

1.64 Nitrogenous 

.90 matter . 22.51 34.23 

1.90 Fat . . . 4.52 8.21 

1.30 Extractives 0.86 0.72 



75.90 Min'l salts 



1.23 



1.45 



THE USE OF ANIMAL FOOD 



According to Mulhall the quantity of animal food used 
per year per capita is as follows in the different countries : 

Pounds Pounds 

United States .... 120 Scandinavia 67 

Great Britain .... 105 Austria 64 

France 74 Spain 49 

Germany 69 Russia 48 

Belgium and Holland . 69 Italy 43 

1 Bischoff & Voit. 2 Konig. 



NITROGENOUS FOODS 285 

COOKING OF MEAT 

The general object of cooking food has already been dis- 
cussed (p. 165). In the case of meat, high temperature 
not only softens the fibers and makes the product more 
agreeable to the taste, but it is only in this way that we 
can be sure that pathogenic bacteria and parasites are 
destroyed. 

The following processes of cooking may be applied to 
meat : boiling, roasting, broiling, baking, stewing, frying. 

In the cooking of meat it is essential to know the object 
desired in the process. If we want an extract, the meat 
should be placed in cold water and kept at a temperature 
below 160° F., for several hours, with the addition perhaps 
of a little salt. This is the method for extracting the nutri- 
tive material for making soup. Recent experiments, how- 
ever, show that there is not as much difference in the com- 
position of meats immersed in cold water and then cooked 
at 85° C, and those plunged at once in boiling water and 
cooked at 85° C, as was formerly supposed. If, on the 
other hand, we desire to retain the rich juices in the meat, it 
must be heated as quickly as possible, especially on the 
outside, so as to prevent the escape of these juices with 
their accompanying flavors. 1 This is done most practi- 
cally by broiling the meat, and to some extent by baking or 
roasting. The process of frying meat is very unsatis- 
factory and affords a product that is tough and unwhole- 
some. 

The greater part of the proteins, both animal and vege- 
table, are coagulated at about 170° F. Fats are not as 
much affected by heat as carbohydrates and proteins, but 
when they are heated to a high temperature, they are 

i Grindley, U. S. Dept. Agric, Office Exp. Sta., Bui. 162. 



286 SANITARY AND APPLIED CHEMISTRY 

liable to become partially decomposed. It is reasonable, 
then, to suggest that if meat is boiled, in order to retain the 
juices which it contains, the meat should be plunged into 
boiling water for a few minutes, thereby sealing up the 
juices within the fibers, then lowering the temperature for 
the thorough cooking of the meat. If a small quantity of 
water is used, less of the soluble material will be extracted. 
The average loss in weight when meat is cooked in hot 
water is about 34 %} 

In the process of roasting, especially when the meat is 
" basted," the same method for sealing up the tubes is 
used, so that the juices may be retained. This is still 
better accomplished in broiling or grilling, because the heat 
that is at first applied is more intense and later the meat 
has an opportunity to cook toward the interior, so that 
the flavor is superior and the agreeable extractives are 
largely retained. 

In stewing or preparing a " pot roast," as the heat is 
low and long continued, and as the juices that happen to be 
extracted are all served with the meat, the process is very 
satisfactory. If the temperature in stewing is not allowed 
to rise about 180° F., the meat will fall apart readily, and 
the proteins will not be coagulated, hardened, or rendered 
indigestible. It is an interesting fact that while vegetable 
foods take up water when they are boiled, animal foods 
actually lose water. According to some recent investi- 
gations, 1 the average amount of water in 14 samples of un- 
cooked meats was 70.08 %, while in the 31 samples cooked 
in hot water it was only 57.50 %. 

1 hoc, ciU 



NITROGENOUS FOODS 287 

BEEF EXTRACTS 

There has been much discussion as to the nutritive value 
of beef extracts, and the conclusion seems to be that the 
commercial extracts are not as valuable as a simple beef 
extract made by slightly broiling the beef and then 
squeezing out the juice. It is a mistake to suppose that 
1 lb. of beef extract contains the soluble constituents of 
20 to 30 lb. of lean beef, and that, as Baron Liebig once 
taught, it is equal in nutritive value to this amount of 
beef. This extract lacks many of the most nutritious con- 
stituents, especially the proteins, and probably acts more 
as a stimulant and a substance to rouse the appetite for 
other foods, than as a true food. 1 There are also prepara- 
tions on the market which consist of extract of beef, to 
which some of the meat fiber has been added. They are 
shown by analysis to contain some protein. " Beef 
juices/' which should be made by expression of the juice 
from the raw or slightly heated meat, contain considerable 
protein and are valuable nutrients. 

Referring to the fluid meat preparations, Thompson 2 
says : " Usually they are tired of soon, and do not support 
life long, for, beyond the means employed of condensation 
of food by evaporation of water and compression, it is 
not possible to ' concentrate ' nourishment very much. 
Making food assimilable and more useful is another matter 
from concentrating it in the sense that it can be made to 
support an able-bodied man and supply him with energy 
for a day's work, for example, of mountain climbing." 

The various kinds of meat do not differ in their com- 
position as much as might be supposed. Some contain 

1 Church, "Food," p. 183. 

2 "Practical Dietetics," p. 118. 



288 SANITARY AND APPLIED CHEMISTRY 

more water, some contain more fat. The fats, it will be 
remembered, belong to the same class as the carbohy- 
drates; that is, they are " work and heat producers/' 
and not " tissue formers " like the nitrogenous foods. 
Comparative analyses show that when fat is deposited in 
a muscle, it replaces water, and not protein, so the gain 
in nutritive matter is not attained by the loss of nitroge- 
nous materials. Lean beef may contain 19 % of nitroge- 
nous matter and 72 % of water. Fat pork only contains 
9.8% of nitrogenous matter and nearly 40% of water. 
Some of these foods are more digestible, of course, than 
others. For instance, mutton is said not to be as readily 
assimilated as beef. Veal is supposed to be liable to 
produce intestinal disorders. Since fish x is both a cheap 
and nutritious food, it should be used, in many localities, 
in larger quantities than at present. The United States 
government is making praiseworthy efforts to introduce 
the common varieties of food fishes in all the waters of 
the country, so that fish may be more abundant and 
cheaper. If we compare the analysis of fish with that of 
meat, we notice that the nitrogenous part of fish affords 
more of the gelatin-yielding matter — that is, the collagen 
— and less extractives than meat. There is also much less 
haemoglobin in the flesh and blood of fish than in meat, so 
the flesh of most fish is of a light color. The mineral 
matter is usually high, and contains a considerable quan- 
tity of phosphates. Fish does not improve, like meat, by 
being kept, even on ice, but it rather deteriorates. 

Fish may be conveniently divided into two classes, — 
the lean and fat. Some examples of these are the follow- 
ing : 2 — 

i Bui. 28, Office of U. S. Dept. Agric. Exp. Stations. 
2 Farmers' Bui. 85, U. S. Dept. Agric. 



NITROGENOUS FOODS 289 

PER CENT OF FAT 
Fat Fish Somewhat Fat Lean 

Eels .... 18 Halibut . 2 to 10 Cod .... 0.4 

Salmon ... 12 Mackerel . 2 to 9 Haddock . . 0.3 

Herring ... 8 Mullet . 2 to 3 Trout ... 2.1 

Turbot ... 12 Bass .... 2.8 

There is more waste matter, such as skin and bones, in 
fish than in meat, and the per cent of water is very high, 
especially in the lean varieties. As fish contains consider- 
able gelatin-yielding substances, it loses more on boiling 
than does meat, hence this is not a good method for cook- 
ing fish. 

Oysters are easily digested, but, as they contain 88% 
of water, they are not regarded as a valuable food from a 
purely nutritive standpoint. They contain both carbo- 
hydrate (glycogen) and nitrogenous matter, though it is 
probable that the latter is not all present in the form of 
proteins. Most of the other shellfish are not as digestible 
as oysters. 

Meats are liable to be dangerous to consumers on ac- 
count of the diseases with which the animals have been 
affected. This is especially the case with pork, which is 
liable to be infected with tapeworms, trichinae, and other 
parasites. The only safe method to be employed, if we 
use pork, is to see that it is thoroughly cooked. Ham, for 
instance, unless boiled for a long time, is not heated to a 
high enough temperature to destroy the parasites. Most 
of the varieties of game are wholesome, and, where abun- 
dant enough to be reasonable in price, are very important 
foods. The same may be said of the so-called sea foods. 
Many of these furnish the protein bodies in a very concen- 
trated form, so, if we use this kind of food exclusively, it is 



290 SANITARY AND APPLIED CHEMISTRY 

not a well-balanced ration.' It is a familiar fact that sail- 
ors on long voyages or those living in nearly inaccessible 
regions suffer severely from scurvy if they are obliged to 
subsist on salt meats without potatoes or other vegetables. 

* Experiment 153. Procure some " Hamburg steak/' and 
weigh out about 25 grams. Put this into 100 cc. of boiling 
distilled water and boil for 30 min. Keep the volume of the 
liquid constant by the addition of more water. Filter, while 
hot, through a cloth, and wash with hot water until the filtrate 
measures 200 cc. Evaporate this filtrate in a weighed dish, to 
dryness, cool, and weigh, and from this calculate the per cent 
of soluble matter obtained. 

* Experiment 154. Weigh out a similar amount of steak 
and add to it 2 grams of salt. Carry out the experiment as 
in Experiment 153, subtract the 2 grams of salt from the weighed 
residue, and calculate the per cent of soluble material. 

* Experiment 155. Weigh about 25 grams of steak, place it 
in a beaker in 100 cc. of cold water, and digest on a water bath 
at a temperature not above 80° G. (176° F.) for 2 hr., then 
filter, and proceed as in Experiment 153. Find the per cent of 
soluble material. 

* Experiment 156. Weigh out 25 grams of steak, and treat 
as in the previous experiment, except adding 2 grams of salt. 
Find the per cent of soluble material, after subtracting the 2 
grams of salt added. 



CHAPTER XXII 
EGGS 

As the egg contains all the substances necessary for the 
development of the chicken, and to sustain it until hatched, 
its composition is of special interest. Over 1800 million 
dozens of eggs are produced annually in the United States. 
Eggs contain much protein and mineral matter, which is 
used to furnish the salts of the bones, especially calcium, 
phosphate, and also fat, one of the most concentrated forms 
of nutriment. The average weight of a hen's egg is 60 
g. (2 oz.), and of this the shell weighs 6 g., the white 36, 
and the yolk 18. The shell consists mainly of calcium 
carbonate. 

The white always has an alkaline reaction, and consists 
of a solution of protein inclosed in numerous cells. When 
the egg is beaten, the cells are ruptured and the protein is 
set free. 

EGG WHITE 

According to Church, 1 egg white has the following com- 
position : — 

Water 84.8 

Albumin 12.0 

Fat, sugar, 2 extractives, membranes .... 2.0 

Mineral matter . 1.2 

i "Foods," p. 160. 

2 The amount of sugar is probably not over 0.5 per cent, according to 
Lehman. 

291 



292 SANITARY AND APPLIED CHEMISTRY 

The nitrogenous material or albumin consists of at least 
four distinct compounds, all quite complex in structure. 
These contain carbon, hydrogen, nitrogen, sulfur, phos- 
phorus, and oxygen, but it is not at present possible to 
state their exact formula. 

EGG YOLK 

The yolk is much richer than the white, as the following 
analysis shows : — 

Water 51.5 

Casein and albumin 15.0 

Oil, lecithin, etc 30.0 

Pigment, extractive, etc 2.1 

Mineral matter 1.4 

The composition of the white and yolk together as 
compared with meat is as follows : 1 — 

Egg Moderately 

Lean Meat 

Water 73.7 73.0 

Protein 14.8 ■ ' 21.0 

Fat 10.5 5.5 

Ash 1.0 1.0 

So eggs may with propriety be used to supplement food 
rich in carbohydrates and lacking in proteins and fat. 
Fat " ham and eggs " do not form a well-balanced diet, 
but potatoes or bread with eggs form a good diet. It is 
estimated that from 15 to 20 eggs are the nutritive equiva- 
lent of 2 lb. of medium fat meat. 

For the preservation of eggs, a large number of methods 
have been proposed, such as packing in bran, coating with 
vaseline or gelatin, and covering with brine or limewater. 

1 Atwater, Bui. 28, Office of Exp. Sta. U. S. Dept. Agric. 



EGGS 293 

The best method, however, has been found to be by cover- 
ing with a 10% solution of water glass (sodium silicate). 1 
As these eggs break readily on boiling, they should be 
pierced with a needle before being put into the water. 

Desiccated eggs have been recently put upon the market. 
If fresh eggs are used in this preparation, there is no reason 
why it should not be possible to furnish a good article of 
diet, when the water has been driven off by drying in 
thin layers, in a current of warm air. The temperature 
employed is one that will give as rapid drying as possible 
without coagulating the albumin. A good quality of 
dried egg should contain 7 % or less of moisture, 37 % of 
fat, and about 30% of soluble, coagulable proteins. 

Most of the so-called " egg substitutes " and " custard 
powders " consist chiefly of starch, dried skimmed milk, 
and turmeric, a yellow coloring matter or Victoria yellow ; 
they are, of course, worthless as " substitutes." 

There is a popular notion that hard-boiled eggs are not 
digestible, and experiments made with eggs in the stomach 
lead to the same conclusion. Thus eggs slightly boiled 
have left the stomach in one and a quarter hours, raw in 
two hours, and hard-boiled in three hours. It should be 
noted, however, that raw eggs are only partially digested 
in the stomach, and complete digestion is accomplished 
farther along in the alimentary canal. 

In cooking eggs, especially for invalids, they should be 
placed in water at 170° to 180° F., and allowed to remain 
for 10 min. or less, when the yolk will be found to be more 
coagulated than the white. The egg albumin begins to 
coagulate at 134° F., and it requires some time to heat the 
egg throughout. 

A convenient method for cooking eggs without the use 

1 Farmers' Bui. 103, Dept. Agric, also Bu. Chem., No. 115. 



294 SANITARY AND APPLIED CHEMISTRY 

of a thermometer, is to pour a quart of boiling water into 
a covered vessel and put two or three eggs into this and 
allow them to remain for five or six minutes. The yolk 
actually cooks more readily than the white, and by this 
process the eggs are cooked uniformly throughout. 

Experiment 157. Mix some egg white with water, add a 
drop or two of dilute nitric acid, and notice that it coagulates. 

Experiment 158. Shake some egg yolk in a test tube 
with ether, decant off the clear liquid into a glass evaporating 
dish and allow to evaporate spontaneously. The egg fat will 
remain in the dish. 

* Experiment 159. Prepare some white of hard-boiled egg 
and when cold rub it through a fine sieve. Place a little of 
this egg white in a test tube and add to it a little hydrochloric 
acid (0.2% solution) and some prepared pepsin. Allow the 
test tube to stand in a vessel of water heated to 40° C. for about 
an hour. Notice that the egg white gradually dissolves, or in 
other words the albumin has been gradually changed into pep- 
tone. 



CHAPTER XXIII 

MILK 

In its composition milk suggests blood ; that is, it is a 
thin watery fluid in which various bodies are held in sus- 
pension and in solution. We can readily see, by the use 
of the microscope, that the fat globules of milk are thus 
held in suspension. It has been shown that the richer the 
milk, the larger these fat globules. The liquid that holds 
them in suspension is rich in nitrogenous matter and 
in sugar. As will be seen from an analysis, milk occupies 
an intermediate position between cereal and strictly ani- 
mal foods. Of the cereal class, it contains milk sugar and 
fat ; while of the animal class it contains casein and 
albumin. Milk is slightly alkaline in reaction. On 
account of the cost of milk in many cities, the poorer 
classes use only limited quantities. For instance, in 
London, an estimate made some time since showed from 
1^ to 7| oz. per capita was used weekly, while in Scotland 
6| pt. was used per week. The composition of milk from 
different animals varies considerably, as can be seen by 
an inspection of the following table : x — 

1 Konig. 



295 



296 



SANITARY AND APPLIED CHEMISTRY 





Spec. 
Grav. 


Water 


Casein 


Albu- 
min 


Total 
Proteins 


Fat 


Milk 
Sugar 


Ash 


Cow's 


1.0315 


87.17 


3.02 


.53 


3.55 


3.64 


4.88 


.71 


Human 


1.0290 


87.41 


1.03 


1.26 


2.29 


3.78 


6.21 


.31 


Goat's 


1.0305 


85.71 


3.20 


1.09 


4.29 


4.78 


4.46 


.76 


Sheep's 


1.0341 


80.81 


4.97 


1.55 


6.52 


6.86 


4.91 


.89 


Mare's 


1.0347 


90.78 


1.24 


.75 


1.99 


1.21 


5.67 


.35 


Ass's 


1.0360 


89.64 


.67 


1.55 


2.22 


1.64 


5.99 


.51 



The specific gravity of milk ranges from 1.027 to 1.035. 
A convenient form of apparatus to use in determining the 
specific gravity is the lactometer, which has a range from 
1.015 to 1.040, and is usually standardized at 60° F. 
(15° C). 

The lactometer was formerly relied upon to detect the 
addition of water to milk, but since the cream may be 
partially removed, and then considerable water added to 
correct the specific gravity, this instrument is not very 
valuable, except for confirmatory tests. 

Experiment 160. Test a sample of milk by a hydrometer 
or lactometer to determine its specific gravity. Readings 
taken at other temperatures than 15° may be corrected by a 
table that has been prepared. 



COMPOSITION OF BUTTER FAT 

By the saponification of butter fat the following compo- 
sition was obtained : x — 



6.13 Oleic acid . . . 

Glycerol (calculated) 
2.09 

49.46 



36.10 

12.54 

106.32 



Butyric acid .... 
Caproic, caprylic, and 

capric acids . . . 
Myristic, palmitic, and 

stearic acids . . . 

1 James Bell, from Allen's "Commercial Organic Analysis," 4th edi- 
tion, Vol. II, p. 279. 



MILK 297 

These results, and many others that might be quoted, 
show that butter fat is practically a mixture of various 
esters, those of butyric, palmitic, and oleic acids being the 
most abundant. The amount of stearic acid contained in 
butter is probably very small. The first four constituents 
are those which distinguish butter fat from ordinary fats 
like lard or tallow. It is by the determination of the 
amount of these that the chemist is able to distinguish 
between genuine butter and its imitations. 

The amount of fat varies from 3 % to 6.5 %, or even 7 %, 
in normal milk. In some countries any milk having less 
than 4 % of fat is considered adulterated, but the minimum 
amount allowed in many cities in the United States is 3 %. 
The Secretary of Agriculture in consultation with the Asso- 
ciation of Official Agricultural Chemists has adopted as a 
" standard" for milk, that it shall contain not less than 
12 % of total solids, and not less than 8.5 % of solids not 
fat, nor less than 3.25% of milk fat. The fat in milk 
can be separated for laboratory purposes by shaking it out 
with ether, and then allowing the ethereal solution to 
evaporate. 

THE BABCOCK TESTER 

A practical method for the determination of fat is the 
one used in large dairies ; that is, by the use of the Babcock 
tester. This instrument, invented by Professor Babcock 
of the University of Wisconsin, has proven of immense 
value to the dairy interests, as it is possible for the pro- 
ducer, as well as the manufacturer, to know exactly the 
value of the milk. The first milk, called the " fore milk," 
which is drawn from the udder of a cow, is poor in fat, 
because the fat globules have risen to the top ; but for the 



298 SANITARY AND APPLIED CHEMISTRY 

same reason, the " strippings," or last of the milk drawn, 
is rich in fat. 

THE SEPARATOR 

The cream may be raised upon the milk by allowing it 
to stand in shallow pans for a long time, by putting it in 
deep vessels and keeping it at a comparatively low tem- 
perature, or more recently, and more practically, by the 
use of the " separator. " This is nothing but a centri- 
fugal machine so arranged that the lighter cream shall, 
when the milk is whirled with great rapidity, come to the 
center and be carried off by a pipe, and the heavier milk 
shall be thrown to the outside by the same motion, and 
carried off to a separate receptacle. 

KOUMISS 

There is a fermented beverage known as " koumiss/' 
made from milk, which should be mentioned. It was 
originally prepared from mare's milk. It is made by mix- 
ing milk with yeast and some sugar, putting it in a bottle, 
and closely corking it. Fermentation takes place after 
two or three days, and the beverage is fit for use. It is 
used as a nourishing tonic for invalids and seldom contains 
as much as 2 % of alcohol. 

Experiment 161. Shake 15 cubic centimeters of milk with 
ether, allow the ethereal layer to separate out, draw it off with 
a pipette, and allow it to evaporate on a watch glass. This 
gives quite a pure grade of butter fat. 

Experiment 162. Determine the amount of butter fat in 
several samples of whole milk by the use of the Babcock tester. 
By the action of oil of vitriol on a measured quantity of milk, 



MILK 299 

a great amount of heat is evolved, and the mixture turns dark 
brown upon the addition of hot water ; when the bottle is put 
into a " centrifuge " and whirled rapidly, the fat, which is 
lighter, collects in the narrow stem of the bottle. The gradua- 
tions of this stem have such a relation to the quantity of milk 
used that the per cent of butter fat can be read directly upon it. 



TOTAL SOLIDS 

The total solid matter in milk is also of use to the 
chemist in forming an opinion as to whether a sample has 
been diluted with water or not. The lowest amount of 
solids usually permitted in normal milk is 12 %, but most 
milk contains from 1 to 3% more. 

Experiment 163. Test the sample of milk, the specific 
gravity of which has been already determined (Experiment 
160) for " total solids, " by weighing a small glass or porcelain 
evaporating dish on the horn-pan balance. Weigh into this 
5 cc. of the sample, and evaporate for about 2 hr., or un- 
til perfectly dry, on a water bath. Weigh the residue, and 
from this and the known weight of the milk, calculate the 
per cent of total solids. Reserve the residue for Experiment 
166. 

CASEIN 

The casein of milk exists apparently in the fresh sample 
as a soluble compound of albumin and calcium phosphate, 
which by the action of " rennet/ ' a ferment from the calf's 
stomach, is converted into an insoluble compound known as 
casein. The casein precipitate of rennet contains from 1 
to 1.5% of ash, consisting almost entirely of calcium phos- 
phate. Lactic acid also precipitates the casein, but the 
precipitate contains less ash than that separated by rennet. 
Mineral acids also precipitate a casein containing less ash. 



300 SANITARY AND APPLIED CHEMISTRY 

The proportion of albumin in milk is always, according to 
Blyth, about one fifth of the casein. 

The proteins of milk contain about 80% of casein, 
which is not coagulated by heat but is coagulated by acids, 
about 15 % of lactalbumin, which is soluble and coagulates 
by heat and forms the skin on boiled milk, and a few minor 
ingredients. 

In the souring of milk, which is caused by certain acid- 
forming bacteria, part of the milk sugar is changed into 
dextros and galactose, and the latter sugar changes to 
lactic acid : — 

Ci2H220n,H20 = C6H12O6 + C6H12O6. C6H12O6 = 2 C3H6O3. 

Lactose Dextrose Galactose Galactose Lactic Acid 

This coagulates the casein, but when a certain degree of 
acidity is reached the ferment is killed, and the action 
stops. This suggests the change that takes place in wines, 
for there also, as the alcohol increases, the ferment is de- 
stroyed. Coagulated milk is frequently used to make a 
kind of cheese which undergoes what is known as " butyric 
fermentation/ ' producing an odor that by some is con- 
sidered very disagreeable. 

MILK SUGAR 

After the casein has been separated from the milk by 
means of rennet, the whey, which remains, may be uti- 
lized for making milk sugar. The crystals undergo lactic 
fermentation readily, but alcoholic fermentation with 
difficulty. 

Experiment 164. To 10 cc. of milk add a few drops of 
rennet, and keep the solution at a temperature of 40° C. for some 
time. A heavy precipitate of calcium paracaseate (cheese) 
results. 



MILK 301 

Experiment 165. Treat a sample of skim milk in a test 
tube with just enough dilute HC1 to cause it to coagulate, 
keep warm for some time, filter and wash. Burn a little of 
the " curd " which remains on the filter, and notice, from the 
odor, its nitrogenous character. Neutralize some of the filtrate 
(the whey) carefully with sodium hydroxid, and test it for milk 
sugar. 

ASH 

The ash of milk consists essentially of phosphates and 
chlorids of potassium, sodium, calcium, and magnesium — 
salts that are especially needed for the growth of bone 
material in the young. A small quantity of citric acid 
is also found in milk in combination with lime. 



STERILIZED AND PASTEURIZED MILK 

Although milk which is drawn from a healthy, clean 
cow by clean hands into a bottle which has been sterilized 
is a sterile fluid, yet in ordinary practice these conditions 
are not attained, and ordinary milk contains a variety of 
microorganisms. Some of these may produce souring and 
others may be bearers of disease. These organisms can be 
destroyed by a temperature of 100° C, and a temperature 
of 75° C. will destroy most of the pathogenic bacteria. This 
process of heating is known as sterilizing, and although it 
is advocated for the treatment of milk for infants and in- 
valids, especially in large cities, yet the quality of the 
milk is decidedly altered. 

Some of the changes noticed in sterilized milk are : — 

1. A change of taste. 

2. The amylolytic ferment is destroyed. 

3. The fat is not so easily emulsified, and cannot be so 
readily absorbed from the intestine. 



302 SANITARY AND APPLIED CHEMISTRY 

4. The casein does not coagulate so quickly, and there- 
fore is not as digestible. 

5. The lact albumin is destroyed. 

PASTEURIZATION 

On account of these changes produced by sterilization 
the method of Pasteurization has come into vogue, except 
in those cases where the milk must be kept for several 
days. Pasteurization consists in keeping the milk at a 
temperature of 167° F., for 20 minutes, instead of raising 
the temperature to the boiling point, as in sterilizing. By 
this process most of the bacteria that are liable to be 
present in the milk are destroyed, the taste of the milk is 
not so much altered, and its nutritive qualities are not 
seriously interfered with. This milk will keep only one or 
two days under ordinary conditions. 

CONDENSED AND EVAPORATED MILK 

It is extremely convenient under some circumstances 
to have at our disposal condensed, or evaporated, milk. 
This may be made from " whole " milk or from skimmed 
milk, and it may or may not be preserved with cane sugar. 
There is one product on the market which is obtained by 
boiling the milk first in open pans and then in vacuum pans. 
This product is served to customers fresh, and will only 
keep for a few days. Another product, one which is more 
commonly used in the United States, is canned or evapo- 
rated milk. This is made by boiling down the milk in a 
vacuum pan and mixing with cane sugar and sealing in the 
cans while hot. This product will keep for a long time, 
but not indefinitely, as it is liable, after a time, to become 
ropy and unfit for use. 



MILK 303 

According to a report of the Massachusetts State Board 
of Health, the following is the analysis of a normal con- 
densed milk: total solids, 74.29%; milk solids, 32.37%; 
cane sugar, 41.92%; milk sugar, 11.37%; proteins, 
8.46 % ; fat, 10.65 % ; ash, 1.29 % ; number of times con- 
densed, 2.3. 

United States standard condensed milk should contain 
not less than 28 % of milk solids, of which not less than one 
fourth is milk fat. Although it must be admitted that in 
some cases condensed milk can be digested more readily 
than fresh milk, yet in general its chief defect is that it 
contains too little fat ; that is, the dilution that is necessary 
on account of the large amount of sugar present, reduces 
the per cent of fat much below that of normal milk. 

One of the newest milk products on the market is " dried 
milk." This product, as well as " dried cream," is made 
by feeding continuously a thin sheet of milk between two 
steam-heated cylinders, revolving in opposite directions, 
and having a surface temperature above 100° C. The 
cylinders are slightly separated, and the milk is dried in 
30 seconds, and scraped from the rolls by a knife edge. 
The product is mixed with warm water for use, 

MODIFIED MILK 

From an inspection of the table given on p. 296, it 
will be seen that human milk differs from cow's milk in 
several important particulars. The latter contains a little 
less fat, considerably less sugar, more proteins, and more 
ash. On this account a great demand has arisen for cow's 
milk so modified that it shall approximate human milk in 
composition. The general method adopted to render 
common milk better adapted to the feeding of infants is 
to bring the proteins and ash to the right proportions by 



304 SANITARY AND APPLIED CHEMISTRY 

dilution with water, then to increase the per cent of sugar 
by the addition of lactose, or sometimes cane sugar, and 
finally to add cream and usually some limewater. 

ADULTERATION OF MILK 

The most common adulteration of milk is by the addi- 
tion of water, but the acid of milk is sometimes neutralized 
by the use of baking soda, or various preservatives may be 
added to it, especially in warm weather. 

Experiment 166. To detect sodium bicarbonate and borax 
in milk, the residue obtained in Experiment 163 is ignited to 
obtain the ash. After cooling, add a drop or two of HC1, 
and notice if there is any effervescence, which would denote 
the presence of carbonates. Test this acidified solution for 
borax by soaking in it, for a short time, a strip of turmeric paper, 
and allowing it to dry on the side of the dish above the solution. 
If the paper becomes of a dark cherry-red color when dry, and 
turns dark olive when treated with dilute sodium hydroxid solu- 
tion, boric acid or borax has been added as a preservative. 

Experiment 167. To test milk for formaldehyde, use 
" Formaldehyde Reagent/'' which is made by adding to a 
liter of hydrochloric acid (1.2 specific gravity) 2 cc. of a 
10% ferric chlorid solution. Ten cubic centimeters of this 
reagent is added to 10 cc. of milk in a small porcelain casserole, 
and the solution is heated, slowly, nearly to boiling, and at 
the same time a rotary motion is given to the vessel to break 
up the curd. When formaldehyde is present there will appear 
a violet coloration, especially when it is partially cooled. The 
color of this solution will vary with the amoimt of formaldehyde 
present. If this preservative is absent, the solution slowly 

turns brown. This test is said to be delicate to if the 

250,000 

milk has not soured. After souring the limit of delicacy is 

. This test cannot be used when the milk is flavored with 

50,000 

vanilla. 



MILK 305 



CHEESE 



The general method of making cheese is by the addition 
of rennet to milk warmed to about 41° C. Rennet is the 
name given to an infusion in brine of the middle stomach of 
the calf. The rennet produces a coagulation of the milk by 
the action of an enzyme, which acts only in an acid or neu- 
tral solution. The coagulated milk, after having been 
broken up several times in vats by the use of knives and 
heated to a moderate degree, is inclosed in cloth and the 
whey is pressed out. After the cheese has become solid, 
the molds are removed and the cheese is placed in well- 
aired rooms to cure. The flavor improves with age, from 
the development of fatty acids and ethers, and by the 
action of certain bacteria. A peptonizing enzyme has 
been discovered in milk, and to this is probably due the 
flavors that are induced in cheese during the process of 
ripening. As this process continues, the cheese is turned 
daily and rubbed with oil. This improvement with 
age suggests what takes place in wines and liquors in the 
process of aging. Some yellow coloring matter, such as 
" annatto " ora coal-tar dye, is frequently added to the 
cheese in the process of manufacture. Cheeses are 
generally classified as cream cheese, whole cheese, and 
skim-milk cheeses. 

Soft cheeses, like Brie, Neufchatel, Gorgonzola and 
Camembert, are made in a short time, and by coagu- 
lating with rennet at a low temperature ; i.e. below 30° C. 

Medium cheeses are allowed to drain for some time 
without pressure. The English " Stilton " and the Swiss 
" Gray ere " belong to this class. 

Hard cheeses, like " Cheddar/ ' and the common cheese 
of the United States, are made by coagulating at a 



306 



SANITARY AND APPLIED CHEMISTRY 



higher temperature — 30° to 35° — and then thoroughly 
pressing. 

The names applied to cheeses are frequently those of the 
locality from which they originally came. Limburger is a 
soft, fat cheese. Roquefort is made from the milk of the 
ewe. Parmesan is a dry Italian cheese, with a very large 
amount of casein, and a moderate percentage of fat. 
Edam is a Dutch cheese, quite dry, and having a red 
coloring on the outside. The following compilation by 
Woll * shows the average composition of some common 
varieties of cheese. 







Water 


Casein 


Fat 


Sugar 


Ash 


Cheddar 

Cheshire 

Stilton 

Brie 


34.38 
32.59 
30.35 
50.35 
44.47 
31.20 
36.28 
35.80 
38.60 


26.38 
32.51 
28.85 
17.18 
14.60 
27.63 
24.06 
24.44 
52.35 


32.71 
26.06 
35.39 
25.12 
33.70 
33.16 
30.26 
37.40 
30.25 


2.95 
4.53 
1.59 
1.94 
4.24 
2.00 
[4.60 

2.03 


3.58 
4.31 
3.83 
5.41 


Neufchatel 

Roquefort 

Edam 

Swiss 


2.99 
6.01 
4.90 
2.36 


Full cream (average) 


4.07 





It is evident that cheese is made up of about one third 
water, one third nitrogenous matter, and one third fat. 
The mineral matter is also of considerable importance. 

Cheese is so rich in nitrogenous matter, and also in fat, 
that it might properly form a valuable food for the poorer 
classes, while it is used by the more wealthy as a relish. A 
comparison with other animal foods shows very distinctly 
its theoretical value as food. It is rather difficult to 
digest in the stomach, unless finely grated or dissolved, as 
the fat protects the casein from the action of the digestive 
fluids. Protein and fat are often much cheaper in cheese 
than in meat. 

1 Dairy Calendar, p. 223. 



MILK 307 

Rich cheese is very liable to decay, for it furnishes an 
excellent medium for the growth of living organisms. 
The poison tyrotoxicon which produces gastro-intestinal 
irritation and nausea, is developed in milk, ice cream, and 
cheese when the material is stored in dark, damp, filthy 
rooms or cellars, or where vessels used for holding the 
milk are not thoroughly cleaned for use. With proper 
care of the milk there is no danger of the development of 
this poison. 

About the only falsification of cheese, aside from the 
fraudulent sale of skim-milk cheese for full-cream cheese, 
is the so-called " filled cheese/ ' which is made by working 
into the material in the process of manufacture some 
foreign fat, as oleo or lard. 

BUTTER AND BUTTER SUBSTITUTES 

Commercial butter is somewhat granular in appearance, 
and this is considered a very valuable quality of butter. It 
has a fragrant odor and an agreeable taste. It contains 
more or less casein, which causes it to undergo decompo- 
sition if the butter has not been thoroughly washed. 
Butter must be salted in order to preserve it for any length 
of time. The composition of butter fat has been noted 
under the discussion of milk. The proportion of these dif- 
ferent fats varies within slight limits, and on this account 
it is not difficult to distinguish between natural butter 
and oleomargarin, or a butter that has been adulter- 
ated with other fats. Cream which is obtained by the 
use of the separator should be allowed to ripen for some 
time before it is churned into butter. In this process of 
ripening, certain bacteria take an active part, and to such 
a degree is this the case that the variety of bacteria in the 
dairy affect very materially the quality of the butter. In- 



308 SANITARY AND APPLIED CHEMISTRY 

deed it has become the custom in some dairies to import 
bacteria, or some material containing bacteria of a specially 
high grade, so as to make a fine quality of " June butter." 
On the continent of Europe the people purchase butter 
every day for a single day's supply, as the butter is never 
salted, and as it usually contains considerable buttermilk 
it will not keep. Butter has the average composition : 
water, 13.59 % ; fat, 84.39 % ; casein, .74 % ; milk, .50 % ; 
lactic acid, .12%; and salts, .66%. 

RENOVATED BUTTER 

" Renovated," or " Process," butter is, in general, made 
as follows : Old, rancid, and unsalable butter is melted in a 
large tank, surrounded by a hot-water jacket, at a temper- 
ature of about 45° C. The curd and brine are then drawn 
off at the bottom and the scum is taken off from the top. 
Air is blown through the mass, to remove the disagreeable 
odor, and, after mixing with some milk, the mass is 
churned, and then run into ice-cold water so as to make it 
granular in structure. The butter is then ripened, 
worked to free it from buttermilk, and salted. Some 
states require that this should be marked " Renovated 
Butter " when exposed for sale, while others allow dealers 
to handle this product without restriction. 

OLEOMARGARIN 

The manufacture of artificial butter, butterine, or oleo- 
margarin has received encouragement, both in the United 
States and abroad, on account of the low cost, and also 
because the imitations are frequently better and more pala- 
table than low grades of cheap butter. The materials 
used in the manufacture of artificial butter are : " neu- 
tral " or leaf lard, from 25 to 60 % ; oleo oil, from 20 to 



MILK 309 

50%: some vegetable oil, like cottonseed oil, from 5 to 
25% ; milk or cream, from 10 to 20% ; butter, from 2 to 
10 or 12% : salt and annatto or aniline coloring matter. 
For different grades of oleomargarin different quantities 
of these substances are used. 

" Neutral " is made by melting leaf lard, and allowing it 
to " grain " by letting it stand at a temperature favorable 
for the separation of the stearin in coarse grains. Oleo oil 
is made in immense quantities, both for use in the manu- 
facture of butterine in the United States, and for shipment 
abroad. The process of manufacture is to cut the beef fat 
into small pieces and " render " it in water-jacketed kettles 
at the lowest possible temperature that is practical. The 
scum which separates at the top is drawn off and the scraps 
settle to the bottom. The liquid fat is then run into vats, 
where it becomes partially cool. The semiliquid mass is 
wrapped up in cloths and pressed to remove the liquid oil 
from the solid fat. The solid fat, known as oleo-stearin, 
is used in the tanning and leather trades, by candle makers, 
for the manufacture of soap and of " compound " lard. 
The oleo oil is used in the manufacture of oleomargarin. 

For the manufacture of oleomargarin certain proportions 
of the ingredients, mentioned above, are churned and run 
into ice water to cool the mass rapidly, and then worked 
like ordinary butter. The particular variety made 
depends upon the market. The manufacturers exercise 
great care that the process shall be a cleanly one, and 
most authorities agree that a good quality of butterine is 
better than a bad quality of butter. 

At the instance of the dairy interests of the United 
States, however, a tax probably intended to be prohibitory 
has been levied upon butterine. This tax is very small, 
| of a cent per pound in case the butterine is not colored, 



310 SANITARY AND APPLIED CHEMISTRY 

but if it is colored in imitation of butter, the tax is 10 
cents. Until this law was passed, the manufacture of 
butterine constantly increased, even though the industry 
was obliged to bear a small tax. In 1903 the total prod- 
uct of oleomargarin was but 71,237,438 lbs., while the 
previous year it was 123,133,852 lbs. ; in 1915 it had in- 
creased to 143,268,730 lbs. 

Experiment 168. Place about 5 grams of butter in a small 
flask, add to it 30 cc. of a solution of potassium hydroxid in 
alcohol, and warm on a water bath. After the soap has had 
time to form, and while some alcohol still remains, add about 
30 cc. of dilute sulfuric acid, and warm the solution. Notice 
the peculiar odor of butyric ether, especially if the solution is 
allowed to stand. 

Experiment 169. Foam test for purity of butter. Heat 
about 3 grams of the sample in a large iron spoon over a low 
Bunsen flame, stirring constantly. Genuine butter will boil 
quietly, with the production of considerable froth or foam, 
which may, on removal from the flame, boil up over the side of 
the spoon. Renovated butter or oleomargarin will sputter 
and act like hot fat containing water, but-will not foam. Exam- 
ine also the curdy particles when the sample is removed from 
the flame; in the case of genuine butter these particles are 
small and finely divided, but in the case of oleomargarin the 
curd will gather in large masses. 

Experiment 170. To make the " milk " test for butter, 
place about 60 cc. of sweet milk in a wide-mouthed bottle, 
which is set in a vessel of boiling water. When the milk is 
thoroughly heated, a spoonful of the butter is added and the 
mixture is stirred until the fat is melted. The bottle is then 
placed in a dish of ice water, and the stirring continued until 
the fat solidifies. If the sample is butter, either fresh or reno- 
vated, it will be solidified in a granular condition and distributed 
through the milk in small particles. If, on the other hand, the 
sample consists of oleomargarin, it solidifies practically in one 
piece, so that it may be lifted by the stirrer from the milk. 



MILK 311 

By the two tests just described, the first of which distin- 
guishes fresh butter from process or renovated butter and oleo- 
margarin, and the second of which distinguishes oleomargarin 
from either fresh butter or renovated butter, the nature of the 
sample examined may be determined. 1 

Experiment 171. To test for coal tar colors in butter, a 
small sample is mixed on a porcelain plate with Fuller's earth, 
and if these colors are present, there will be a red mass, while if 
absent, the color will be only light yellow or brown. 

1 Bigelow and Howard, U. S. Dept. Agric, Bu. Chem., Bui. 100, p. 51. 



CHAPTER XXIV 
NON-ALCOHOLIC BEVERAGES 

The ordinary beverages, not including milk, may be 
classified as non-alcoholic and alcoholic. 

From the earliest time there has been a demand for 
some slightly stimulating beverage that is non-intoxicating 
in character. The simple herb drinks, such as catnip tea, 
sage tea, sassafras tea, etc., have been used and are more 
agreeable than hot water alone, which in itself is slightly 
stimulating. In different countries and under different 
conditions, people selected certain plants which seemed 
to be stimulating in their effects, and made beverages from 
them. It was later found out that the plants so selected 
contained certain active, crystalline principles which were 
stimulating in character. 

The most important beverages at present in use are 
tea, coffee, and cocoa. The imports of tea for the year 
ending June 30, 1915, were 96,987,942 pounds valued at 
$117,512,619. The importation of coffee for the same 
year amounted to 1,118,690,542 pounds, valued at $106,- 
765,644, and that of cocoa products was 194,734,195 
pounds, valued at $23,478,156. 1 The per capita consump- 
tion of these beverages for a single year was for tea 1.30 
lbs., for coffee 10.79 lbs. In Great Britain the per capita 
consumption of tea is four times that of the United States, 
while the per capita consumption of coffee is only one 

i Year Book, U. S. Dept. Agric, 1915. 
312 



NON-ALCOHOLIC BEVERAGES 313 

tenth that of the United States. The use of tea is, how- 
ever, increasing in this country. 

TEA 

About 51 % of our tea comes from China and 42% from 
Japan. The history of the discovery of tea is lost in 
antiquity. The first authentic account was as late as 
350 a.d., while in European literature the earliest record 
appears in 1550. The first consignment of tea into Eng- 
land took place in 1657, and it came into the United States 
in 1711. Genuine tea is prepared from the leaf of the 
Thea sinensis, a plant which grows to the height of 4 to 
5 ft. The leaves are ready for picking at the end of the 
third year, and the average life of the plant is about 10 
years. The leaves are picked at least three times per year, 
— in April, May, and the middle of July. The first pick- 
ings are the best and tenderest, and make the best grade 
of tea. 

CURING OF TEA 

After sorting, the natural moisture is partially re- 
moved by pressing and rolling, then the leaves are dried 
by gently roasting in an iron pan for a few moments. 
They are then rolled on bamboo tables and again roasted, 
and finally separated into the various grades by passing 
through sieves. 

The difference between green and black tea is mainly 
due to the fact that the green is steamed thoroughly and 
then rolled and carefully fired, whereas black tea is first 
made up into heaps which are exposed to the air and al- 
lowed to ferment, and thus the olive-green is changed into 
a black color. 



314 SANITARY AND APPLIED CHEMISTRY 

In the preparation of Japan tea, the leaves are steamed 
in a tray over boiling water. They are then heated on a 
tough paper membrane over an oven and at the same time 
stirred with the hand. The tea after being thus fired 
is dried for some hours and sorted by passing through 
sieves. Then it is sent to the warehouse, where sometimes 
the " facing process " is carried on, by heating the tea in 
large bowls and adding various pigments to it. 

ADULTERATION 

There are but few spurious teas on the market, but the 
range in quality is very great. On account of the strict 
enforcement in the United States of the adulteration act, 
no adulterated tea is permitted to be imported, and the 
consumer is reasonably well protected. He usually 
secures genuine leaves though he may get very inferior 
grades of tea. 

Tea, supplied to the foreign market, is exposed to a 
large number of sophistications and adulterations, mainly 
for giving it an increased weight. These adulterations 
include adding foreign leaves, spent tea leaves, metallic 
iron, sand, brick dust, etc. 

Such substances as catechu or similar materials that 
contain tannin, are added to produce an artificial ap- 
pearance of strength. Another sophistication, which is 
practiced especially on green tea, consists in imparting 
a bright appearance to inferior tea by means of coloring 
matter or facing; for this purpose they use soapstone, 
gypsum, Prussian blue, indigo, turmeric, and graphite. 
Another form of sophistication is practiced on exhausted 
tea leaves by a similar process of facing. It is even said 
to be possible, by careful manipulation, to change black 
tea to green and vice versa. 



NON-ALCOHOLIC BEVERAGES 



315 



VARIETIES OF TEA 

The Indian teas are very much stronger than those from 
China and Japan, so that they produce a beverage that 
seems too strong to those accustomed to Chinese and 
Japanese teas. The Indian teas only come in contact 
with the hands of the workmen at the time of picking. 
The Chinese teas are manufactured almost entirely by 
hand, although sometimes the feet are used in rolling the 
cheaper grades. 

A substance called " lie tea " is frequently put upon the 
foreign market. This consists of fragments of genuine 
leaves, foreign leaves, and mineral matter held together 
by a starch solution and colored with various preparations. 

In England black teas are used much more than the 
green. This is due to the fact that black teas contain 
less astringent matter and also act less upon the nerves. 
By comparison of analysis of black and green tea it is evi- 
dent that there is less material soluble in hot water in the 
former. 1 




Black Tea 



Crude protein 
Fiber . . . 
Ash ... . 
Thein . . . 
Tannin . . . 
Total nitrogen 



38.90 
10.07 
4.93 
3.30 
4.89 
6.22 



The important constituents are the extract, a certain 
amount of tannin and thein, and the volatile oil. On 
account of the presence of a large amount of tannin in tea, 

1 Analysis by Kozai : W. G. Thompson, "Practical Dietetics," p. 211. 



316 SANITARY AND APPLIED CHEMISTRY 

which is extracted by heating with water, it is important, 
in making the beverage, that the water should not stand 
for any length of time upon the leaves. On this account 
a much more wholesome beverage may be made by the 
use of the tea-ball with the hot water. It is a great mis- 
take to allow the tea to draw for hours at a time. Freshly 
boiled water should be used in making tea, and it should 
be thoroughly boiling when poured upon the leaves, and 
allowed to digest about three minutes, not longer. 
Longer infusion will make the tea appear stronger 
but will spoil its delicate flavor, and extract too much 
tannin, which will have an injurious effect on the system. 
The water used should not be too soft, as that will extract 
more soluble material, nor should it be extremely hard. 
The thein is practically all extracted from tea within the 
first five minutes, while the amount of tannin continues 
to increase for 40 minutes or more. The infusion should 
be poured off from the grounds as soon as made. 

According to Hutchison an ordinary cup of tea will con- 
tain nearly a grain of thein, and from 1 to 4 grains of 
tannin, dependent on the kind of tea used. There is no 
direct relation between the quality or price of the tea and 
the proportion of thein. This substance, thein, which has 
the formula C 8 Hi N 4 O2, is an ureide belonging to the same 
general class as guaranin, xanthin, uric acid, etc. The 
volatile oil which is present gives to the tea its agreeable 
flavor and aroma. 

Experiment 172. Make a decoction of tea in a test tube, 
pour it off from the grounds, and test a part for tannic acid. 
First, by ferric chlorid ; 
Second, ferrous sulfate ; 
Third, by a mixture of these two reagents. 
A black or bluish black color (ink) will be produced. 



NON-ALCOHOLIC BEVERAGES 317 

PARAGUAY TEA 

There is another variety of tea known as Paraguay tea, 
or Yerba Mate, which was selected by the people of South 
America to use as a beverage. This tree grows wild, and is 
known to the botanist as Ilex paraguayensis. The tea 
is prepared in Paraguay by cutting off the small twigs and 
leaves and placing them on a clean plot of earth surrounded 
by fire. In this way the leaves are wilted and cured, and 
they are afterward dried on a grating over a fire, and then 
reduced to a coarse powder. The infusion, which is pre- 
pared in a kind of gourd, is conveyed to the mouth by 
means of a reed or a silver tube called a " bombilla," with 
a strainer at the end. 

Mate contains 1.3 % of thein and 16 % of tannic acid, also 
an aromatic oil and gluten. The tannic acid has entirely 
different properties from that contained in tea or coffee. 

COFFEE LEAF TEA 

In some coffee-growing countries the natives use the 
leaves of the coffee tree to make an infusion which has 
about the same constituents and properties as ordinary 
tea. 

COFFEE 

Coffee is the seed of the Coffea arabica, indigenous in 
Abyssinia and Arabia, and this plant, at the present time, 
is grown in Java, the West Indies, in Ceylon, Mexico, and 
Central and South America. It was used in the remotest 
time in Arabia. It was introduced into Constantinople in 
1574; in 1660 it was carried from Mocha to Java, and 
thence specimens of the tree were taken to Holland and 



318 SANITARY AND APPLIED CHEMISTRY 

France. Coffeehouses were opened in London about the 
middle of the seventeenth century. In 1809 the first 
cargo was shipped to the United States. There is a great 
difference in the quality and flavor of coffee from different 
localities. 

The coffee tree is productive for about thirty years. 
The trees are usually planted every twenty years and grow 
best on the uplands. The trees are raised from seeds 
in nurseries and transferred to the plantations. In Java 
the picking of the berry begins in January, and lasts 
three or four months ; in Brazil, the picking begins in 
April and May, and continues throughout the season. 
After the berries are harvested, the first operation by 
which they are treated is called pulping. Sometimes the 
berries are pulped in the soft state, sometimes they are 
first dried, and then the dried skins are removed by a 
machine called a huller. The West Indian and Brazilian 
method is to macerate the berries in a large vat, where 
they are treated by what is known as a pulping machine, 
which is an iron cylinder set with teeth, which removes 
the outer covering. The loosened pulp is carried out at 
one side and the berries sink to the bottom of the vat. The 
berries are afterward dried, cleaned, and sorted. 

The next process is the roasting of the bean. This may 
be carried on directly over a fire or in an oven. The 
average loss of weight in the process of roasting is about 
16%. This process develops an essential oil and brings 
out the aroma of the coffee. If the operation is carried 
too far, the best properties and ingredients are lost. 

The following analysis by Konig shows the difference 
between raw and roasted coffee : — 



NON-ALCOHOLIC BEVERAGES 



319 





Per Cent 




Raw 
Coffee 


Roasted 
Coffee 


Water 


11.23 
1.21 

12.27 

8.55 
18.17 
12.07 
32.58 

3.92 


1.15 


Caffein 


1.24 


Fat 


14.48 


Sugar 


.66 


Cellulose 


10.89 


Nitrogenous substance 

Other non-nitrogenous matter . . . 
Ash 


13.98 

45.09 

4.75 







The effect of roasting is to drive off a large part of the 
water, and to caramelize most of the sugar. The bean 
becomes more brittle, and the caffeol 1 (C 8 Hi O 2 ), to which 
coffee largely owes its odor and flavor, is, at the same time, 
developed. The active principle, called thein, or caffein 
(C 8 HioN 4 02), is believed to be identical with that of tea. 
The infusion of coffee also contains some nitrogenous 
material. 



ADULTERATION 

Ground coffee is especially liable to be adulterated. 
Some of the chief substances added to the commercial 
ground coffee are chicory, caramel, peas, and roasted 
grains, such as corn, wheat, and rye. There has also 
been found upon the market an artificial coffee bean which 
contains absolutely no coffee, and is made by compression 
of harmless, starchy ingredients into the form of the coffee 
bean. This is mixed with the genuine beans. The raw 
coffee bean is sometimes subjected to the process of sweat- 

1 Hutchison, "Food and Dietetics," p. 310. 



320 SANITARY AND APPLIED CHEMISTRY 

ing, by which it is increased in size and improved in color 
and flavor; it is sometimes moistened with water con- 
taining a little gum and colored with various pigments, 
such as Prussian blue and turmeric, so as to improve its 
appearance. In this way, for instance, Mexican coffee 
is made to resemble Java coffee. 

THE BEVERAGE 

In regard to making the beverage there are two com- 
mon methods, either of which may be used. The first is 
to put ground coffee into cold water and bring the decoc- 
tion to the boiling point. The second, and probably 
better, method is to have the water boiling tumultuously 
and add to it the required amount of finely ground coffee, 
boil not more than three minutes, and then serve immedi- 
ately. The beverage is also made by " percolation " or 
pouring boiling water through the finely ground coffee, 
and by a " decoction " process which is the method em- 
ployed in preparing Turkish coffee. If the coffee is 
allowed to boil for any length of time, not only is the 
tannin extracted from the berry, but the agreeable aroma 
and flavor is lost, as it is carried off with the volatile oil. 
The coffee is then not as wholesome, and it certainly is not 
as agreeable in flavor. 

Many persons find that black coffee produces less ill- 
effects upon the system than does coffee served with cream. 
This may be due to the compound produced by the action 
of the tannin of the coffee upon the protein substances of 
the milk. Cafe au lait, which is a mixture of three parts 
of hot milk with one part of coffee, is a popular beverage 
in many countries. It will be noticed that coffee contains 
less of the alkaloid than tea. 

There is no great objection to the substitutes for coffee 



NON-ALCOHOLIC BEVERAGES 321 

that are upon the market, if they are not bought as coffee. 
Many of these are no doubt wholesome enough, and if 
coffee has been found to disagree with the system, it is 
probably better to use some beverage of this kind, which 
is simply an extract of a roasted cereal. 

VARIETIES OF COFFEE 

There are many varieties of coffee upon the market, but 
the Mocha and Java coffees usually command the highest 
price. Comparatively small quantities of these coffees 
are at present available, but coffee grown in other countries 
from the Mocha or Java stock is more abundant. The 
low grades of coffee have decreased very much in price 
during the last few years. This is probably due to the 
competition, and, also, to the fact that immense quantities 
of the cheaper grades are raised in South and Central 
America. The latest official report shows that three 
fourths of the coffee imported into the United States comes 
from Brazil. Some persons have become accustomed to 
the strong black coffee made from the Rio brand, and to 
meet their demand, in "blending," some Rio is often 
added to other grades. 

COCOA AND CHOCOLATE 

The raw material from which cocoa and chocolate is 
made, is the seed of the Theobroma cacao. It grows most 
readily from Mexico to Peru on the west coast of the 
American continent, in Mexico and Brazil on the east 
coast, and in the West India Islands. It was introduced 
into Europe by the Spaniards in 1519. Chocolate was 
first prepared in the United States in 1771, at Danvers, 
Mass. 1 The tree is about 18 or 20 ft. high, blooms con- 

1 Harrington, "Practical Hygiene," p. 174. 
y 



322 



SANITARY AND APPLIED CHEMISTRY 



tinuously, and yields two crops a year. The lemon- 
yellow fleshy fruit is about 7 in. long, something like a 
short cucumber in appearance, and has ten longitudinal 
ridges. The seeds are arranged in five rows in the pulpy 
flesh. There are two processes for preparing the seed 
for the market. For unfermented cocoa the seeds are 
separated from the pulp and dried in the sun; for the 
fermented cocoa the seeds are placed in piles and allowed 
to ferment, before being dried. Much of the acridity and 
bitterness disappears in this process of fermentation. The 
principal operations in the process of manufacture are, first, 
the sifting of the raw cocoa to remove the sand and dust ; 
second, the separation by hand of the larger stones and 
empty pods, etc. ; third, roasting the cleaned seeds. 

The following table * shows the composition of some 
cocoa products : — 



Water 

Ash 

Theobromin .... 

Caffein 

Other nitrogenous sub- 
stances (protein) . . 

Crude fiber 

Sugar 

Pure starch 

Other nitrogen-free sub- 
stances 

Fat 



5 « a 



6.23 

5.49 

1.15 

.16 

18.34 
4.48 

11.14 

26.32 
26.69 



ra -q O od 



H h O od 

3 6 3 * 



4.87 

10.43 

.49 

.16 

14.46 
16.55 

4.13 

46.15 
2.76 



fc r-T & « 
5 g ° H 

On d O J 
O < <J 

H O « ^ 

t> W ^ 



3.78 

3.15 

.78 

.13 

12.36 

2.86 

18.11 

16.64 
52.19 



t" 1 fa s 

Mas 

H o « 3 

^o^2 



2.17 

1.40 

.35 

.08 

4.58 
.95 

56.44 

2.88 

7.64 
23.51 



1 Rep. Conn. Agric. Exp. Station, 1903, Pt. II, p. 125. 



NON-ALCOHOLIC BEVERAGES 323 

Cocoa is not only used to make a pleasant and exhilarat- 
ing beverage ; it is a valuable food material. The most 
important constituents are fat, theobromin, which is the 
alkaloid or, properly speaking, the ureide of cocoa, a 
little starch, and some albumin and fibrin. The fat usually 
forms about 50% of the husk and bean. It is a mixture 
of the glycerids of stearic, palmitic, lauric, and arachidic 
acids, and is extensively used in pharmacy under the 
name of " cocoa butter. " Theobromin, which was dis- 
covered in 1841 by Woskresensky, is very closely related 
to xanthine, being dimethyl xanthine, CsH^CHs^N^. 
Caffein is trimethyl xanthine, C 5 H(CH3)3N 4 02. 

COMMERCIAL PREPARATIONS 

The commercial preparations of cocoa are quite numer- 
ous. Plain chocolate is prepared by grinding roasted and 
husked seeds to a paste and pressing in the form of cakes. 
When this is combined with sugar, vanilla, etc., sweet 
chocolate is the product. Since there is so much fat in 
the cacao, this is frequently partially removed, and the 
residue is put on the market under the name of cocoa. 
Cocoa shells or husks are sometimes used for making an 
exceedingly weak beverage of this class, which contains 
little fat, but considerable nitrogenous matter and extrac- 
tives. Cocoa " nibbs " are the bruised, roasted seeds, 
and contain all the fat. The names that are applied to 
the different preparations of cocoa and chocolate vary in 
different countries. Cocoa and chocolate preparations are 
very readily adulterated, but, after all, the general adul- 
terants, if such they may be called, are sugar and starch, 
which are not injurious, but only decrease the cost for the 
benefit of the manufacturer. The genuine or " bitter " 
chocolate should contain all the original fat. An inferior 



324 SANITARY AND APPLIED CHEMISTRY 

vanilla chocolate is flavored with the artificial vanillin and 
coumarin in place of the finer flavored vanilla bean. 

It is said that the term " soluble cocoa " is erroneous, as 
very little of the albuminous substances or the fat are 
soluble. In order to grind the bean to a very fine powder 
it must be mixed with sugar or starch, and this, in fact, 
is the method used in the preparation of some of the 
powders recommended for invalid diet. Sometimes, in 
order to make a cocoa that shall be more digestible, a part 
of the fat is saponified by the use of sodium hydrate and 
magnesia, a process that may in some cases produce a 
food that is less digestible than the product that is not so 
treated. 

Sweet chocolate, especially by reason of the sugar that is 
added, has a high food value. Chocolate does not, like 
tea and coffee, produce wakefulness, though, on account 
of the large amount of sugar and fat which it contains, it 
may produce indigestion. As chocolate is a concentrated 
food, it may be conveniently used when the weight of 
food to be carried must be considered, as on the march, 
or on camping expeditions. 

Experiment 173. Shake a few grams of powdered chocolate 
in a test tube with ether, filter, on a dry filter, and allow the 
filtrate to evaporate spontaneously in a glass evaporating dish. 
Notice the taste and odor of the fat or " cocoa butter " that 
remains. Notice also that cocoa butter gives a clear solution 
with ether, while wax or tallow gives a turbid solution. 

Experiment 174. Boil a few grams of powdered chocolate 
with water, filter off 10 cc, and treat the cold solution with 
iodin reagent for starch. 

COLA 

The cola nut grows on a small tree in several tropical 
countries, especially Jamaica, Africa, East India, and Cey- 



NON-ALCOHOLIC BEVERAGES 325 

Ion. It contains caffein, theobromin, tannin, and the 
other constituents of tea and coffee. As a beverage it is 
made into an infusion like coffee, and is served with milk 
and sugar. 

COMPARISON OF THE COMMON STIMULATING 
BEVERAGES 

These beverages possess qualities in common for which 
they are universally esteemed by mankind. First, they 
retard the retrograde metamorphosis of the body tissues, 
and thus enable the work of the individual to be done upon 
a smaller supply of food material and with less fatigue. 

Second. When used in moderation, they are all more 
or less stimulating to the mental powers. 

Third. They act as sedative to the nervous system. 
The similarity of the action of these beverages is due to the 
possession of common constituents. While there are 
divergences from each other, in their finer shades of action 
their value depends upon the aromatic and volatile oil 
which modifies the action of the alkaloid. It is an interest- 
ing fact that similar properties are developed in each of 
them by roasting and drying. 

Coffee is more stimulating than cocoa. It is apt to 
cause irregularity and palpitation of the heart and may, 
if boiled too long, disorder digestion. 

Tea is the most refreshing and stimulating of these bev- 
erages. Used in excess, however, it powerfully affects 
stability of the motor and vasomotor nerves, the action of 
the heart and the digestive functions, producing dyspepsia, 
tremulousness, irregular cardiac action, headache, etc. 

Mate is supposed to be intermediate in its effects between 
tea and coffee. Chocolate is more nutritious than tea or 
coffee on account of the amount of fat which it contains ; 



326 SANITARY AND APPLIED CHEMISTRY 

although much of this fat is removed in making cocoa. 
Since but little of the solid is used in making the beverage 
cocoa or chocolate, the food value is not very great. 
Cocoa and chocolate are only slightly stimulating in their 
effects. 

Cola probably has a restraining influence on tissue waste 
and is mildly stimulating to the heart and nervous system. 
As it will increase the endurance, it may be used when 
severe muscular exercise is to be undertaken. 

When we consider the whole subject of beverages of this 
class, it is extremely interesting to notice that uncivilized 
people and civilized people in different ages of the world, in 
different climates, and under entirely different circum- 
stances, have chosen plants to use in the manufacture of 
beverages that contain these alkaloid principles ; caffein in 
the case of tea, coffee, and cola, and theobromin in the case 
of chocolate. Most of them also contain the astringent 
principle tannin. The use of these beverages has increased 
from year to year in all civilized countries. 



CHAPTER XXV 



ALCOHOLIC BEVERAGES 



It is probably true that alcohol, as such, is not found in 
sound fruit, yet alcohol is so readily formed by the process 
of fermentation from cane or fruit, that it was not 
strange that it was accidentally discovered, and that 
beverages having intoxicating qualities should have been 
used very early in the history of the world. Alcohol, 
C 2 H 5 OH, is a colorless liquid, having an agreeable odor, 
burning with a blue flame, and having a specific gravity of 
.792. Ordinary alcohol is about 95 % strength, and the 
remaining 5 % is water. Proof spirit, as it is called, con- 
tains 42.50% of alcohol by weight or 50% by volume. 
This was originally named from being the most dilute 
spirit which when lighted would fire gunpowder. 

The annual consumption of alcoholic beverages, per 
capita, in the United, States, and in several other countries, 
in 1906 to 1910, 1 was : — 





LlTEES 




Beer 


Wine 


Spirits 


Great Britain 

France 


143. 
71.6 
134. 

76.2 


1.23 
144. 
19.8 

,2.37 


4.17 

8.82 


Austria-Hungary 

Japan, all liquors (mostly sake) . 
United States 


8.20 

16.21 

5.51 



1 " Alcohol and Society, " John Koren. 
327 



328 SANITARY AND APPLIED CHEMISTRY 

The Statistical Abstract of the United States for 1915 
reports the per capita consumption of distilled spirits to be 
1.25 proof gal. ; that of wine, 0.32 gal. ; and that of malt 
liquors, 18.24 gal. There was until recently a notable in- 
crease in the consumption of malt liquors from year to year. 

CLASSIFICATION 

Alcoholic beverages may be made from any vegetable 
product that contains starch or sugar. There are four 
general classes, viz. : — 

1. Fermented liquors : as wine, cider, perry ; wine from 
fruits, berries, etc. ; palm wine, called " toddy " in India; 
bouza, made in Tartary and the East from millet seed; 
honey wine, used in Abyssinia ; koumiss, made from mare's 
milk in Tartary ; fig wine, made in the vicinity of the Medi- 
terranean Sea ; and pulque, made by the Mexicans from 
the juice of the century plant. 

2. Malt liquors : as lager beer, ale, porter, stout ; kvass, 
made in Russia from rye ; chica, made in South America 
from corn, rice, etc. ; sake, made in Japan from rice ; and 
pombe, made in Africa from rice. 

3. Distilled liquors : as alcohol, whisky, brandy, gin, 
and rum, and vodka made from grains in Russia, arrack 
made from rice and palm juice in India, mescal or pulque 
brandy, and cherry brandy, or "Kirschwasser," as it is 
termed, in Germany. 

4. Liqueurs and cordials : as absinthe and vermuth. 
The fermented liquors are made from the juices of fruits, 

which contain sugar, and they require no yeast to start 
the fermentation, but depend on the organisms which are 
present in the natural juices. Most of the sugar present 
in fruits is in the form of invert sugar. As the quantity of 



ALCOHOLIC BEVERAGES 



329 



alcohol that can be obtained from any fruit juice is depend- 
ent on the amount of sugar contained, a consideration of 
the sugar content is important. 

The following analyses, by Fresenius, show the amount 
of sugar and acid in the common fruits : — 



Per Cent 
Sugar 



Per Cent Free 
Malic Acid 



Grapes . . . 
Sweet cherries 

Sour cherries . 

Mulberries . . 

Apples . . . 

Pears . . . 

Gooseberries . 
German prunes 

Currants . . 

Strawberries . 

Blackberries . 
Raspberries 

Green grapes . 

Plums . . . 

Apricots . . . 

Peaches . . . 



16.15 
15.30 
10.44 
10.00 
9.14 
8.43 
8.00 
7.56 
7.30 
6.89 
5.32 
4.84 
4.18 
2.80 
2.13 
1.99 



.80 

.88 

1.52 

2.02 

.82 

.09 

1.63 

1.08 

2.43 

1.57 

1.42 

1.80 

.67 

1.72 

1.25 

.85 



WINE 

The most important of the fermented beverages is wine. 
The cultivation of grapes, for the purpose of making wine, 
began in the East in the earliest times, and extended along 
the shores of the Mediterranean Sea. Germany, Austria, 
Greece, France, Italy, Spain, and Portugal are the con- 
tinental wine-growing countries, while in the United States 
the industry is of great importance in Ohio, New York, 
Virginia, and California. The quality of the wine depends 
on the variety of grapes, the soil, climate, and even on the 
weather. 



330 SANITARY AND APPLIED CHEMISTRY 

In order to make genuine wine, the grapes are allowed 
to ripen, so that they contain as much sugar as possible. 
The grapes are carefully crushed and pressed, and the first 
juice that runs off produces the best quality of wine. 
The " marc," as the pulp is called, is sometimes pressed 
several times after being soaked with water, and this 
affords cheaper qualities of wine. The " must," as the ex- 
pressed juice is called, is allowed to ferment from 10 to 30 
days. Fermentation begins at from 10° to 15° C, and is 
brought about by the germs which grow at the expense of 
the saccharine and albuminous substances present, and 
change the sugar to carbon dioxid and alcohol. Thus : — 

C 6 H 12 6 = 2C 2 H 6 + 2G0 2 . 

Sugar Alcohol Carbon Dioxid 

After the first fermentation, the wine is drawn off from 
the " lees " and put in casks, where the after fermentation 
takes place. The " lees " consist of the fungus growth, 
some calcium salts, coloring matter and " argols," potas- 
sium bitartrate, or " cream of tartar," which is insoluble in 
dilute alcohol. This is the only practical source of cream 
of tartar ; consequently this chemical commands a good 
price. 

From 69 lb. to 70 lb. of " must " can be obtained from 
100 lb. of grapes. The quantity of sugar in the juice varies 
from 12 to 30 %. It is of importance that the ferment be 
of a certain kind to produce a good wine; and, indeed, 
the bacteriologist has begun to propagate special cultures 
of a pure yeast to produce wine of a desired flavor. The 
wine is stored in casks for some months, for the process of 
aging. Before being placed in the cask, the wine is treated 
with isinglass, or egg albumen, and " racked off " from the 
deposited impurities. It must not be too freely exposed 
to the air,, as there is danger that the alcohol, by the aid of 



ALCOHOLIC BEVERAGES 331 

the acetic ferment, shall be changed to acetic acid, accord- 
ing to the reaction, — 

C2H5OH + 2 2 = C 2 H 3 O.OH + 2 H 2 0. 

During the aging process a variety of fragrant ethers, as 
acetic ether, malic ether, etc., are formed, which produce 
an agreeable odor or bouquet. Wines are sometimes aged 
and at the same time preserved, by pasteurization, which 
consists in heating them for some time at 60° C, with a 
limited supply of air. 

In regard to the changes that take place in the cask, 
Leach observes that the alcoholic strength of the wine rises. 
This is due to the fact that the water of the wine soaks into 
the wood more than the alcohol and is lost by evapora- 
tion, so that the wine becomes more concentrated. As 
the water so lost is replaced by the addition of more w T ine, 
the increase in the proportion of alcohol is rendered all the 
greater. In the cask, too, a partial oxidation of the tannic 
acid takes place. This causes the white wines to become 
darker in color, but has just the reverse effect upon the 
red wines ; for the oxidized tannic acid unites with and 
precipitates some of the pigment. 

STRENGTH OF WINE 

The alcoholic strength of the wine is somewhat increased 
by a further fermentation of the sugar. By the oxidation 
of some of the alcohol to acetic acid, compound ethers are 
formed. There is an impression that wine continues to 
improve with age, and " old wine " is highly prized. 
Some of the stronger wines improve for a few years, but 
not for an indefinite time, and wines often begin to 
deteriorate after a short time. The " extract, " as the 
term is used below, is what remains upon evaporation. 



332 



SANITARY AND APPLIED CHEMISTRY 



The following table gives the composition of a few 

wines : — 

Composition of Wines 





Alcohol 


Extract 


Free Acid. 

Tartaric 


Sugar 


Ash 


French red . 


7.80 


2.97 


,58 


.46 


.25 


French white 


10.84 


1.26 


.44 


.88 


.20 


Spanish red . 


12.34 


3.84 


.57 


.25 


.75 


Calif, red . 


10.03 


2.11 


.64 


.25 


.34 


Calif, white . 


11.16 


11.80 


.63 


.20 


.17 



Sweet Wines 





Alcohol 


Extract 


Free Acid. QT- rAT? 
Tartaric ^ UGaR 


Ash 


Champagne . 
Port . . . 
Sherry 
Madeira . . 


9.50 
16.29 
15.93 
15.49 


14.34 
8.30 
5.00 
5.61 


.58 

.38 

.48 
.41 


.75 
6.26 
2.76 
3.18 


.16 
.25 
.56 
.33 



CLASSIFICATION OF WINE 

Wines are either natural or " fortified. " Natural wine 
contains no added alcohol or sugar. When the pure juice 
of the grape is allowed to ferment, if it contains sufficient 
sugar, the amount of alcohol will continue to increase until 
the wine contains about 15%, and this amount of alcohol 
prevents any further fermentation. Hock and claret are 
usually of this class. When alcohol is added to the wine, 
it is said to be " fortified." Port and Madeira are often 
treated in this way. 

Wines are divided into red and white wines, from the 



ALCOHOLIC BEVERAGES 333 

color ; also into dry wines, or those in which all the sugar 
has been changed to alcohol ; and sweet wines, or those in 
which some sugar still remains, although these are often 
reenforced by the addition of grape sugar. Dry wines are 
consequently slightly sour. Wines are also divided into 
" still " wines, or those in which the carbon dioxid gas 
has been allowed to escape ; and effervescent wines, in 
which the carbon dioxid has been retained in the liquid 
under pressure. 

Grapes make better wine than other fruit because the 
potassium bitartrate (KHC 4 H 4 0e) is precipitated as the 
alcohol becomes stronger in the process of fermentation. 
Other fruits and berries, on the other hand, contain citric, 
malic, or succinic acids, and the salts of these are not pre- 
cipitated during fermentation, and so this wine has not the 
agreeable taste that characterizes grape wine. 

ADULTERATION OF WINES 

The adulterations of wine are very numerous. Plaster 
of Paris is often used abroad for the adulteration of wines, 
but native wines and those imported into the United States 
are usually free from this material. This is done, it is 
said, to clarify it, to improve the color, to make the 
fermentation more complete, and to improve the keeping 
qualities. On the other hand, this process is supposed to 
leave some injurious compounds in the wine. The re- 
action due to " plastering " is as follows : — 
2KHC 4 H 4 6 + CaS0 4 = CaC 4 H 4 6 + H 2 C 4 H 4 6 + K 2 S0 4 . 

Pot. Bitartrate Cal. Sulfate Cal. Tartrate Tartaric Acid Pot. Sulfate 

In France there is a law against the addition of more than 
a limited quantity of plaster of Paris to wines intended for 
home consumption. Not over .2 % of potassium sulfate is 



334 SANITARY AND APPLIED CHEMISTRY 

allowed to be present. The wine manufacturers also burn 
sulfur in the casks so that the sulfur dioxid shall artifi- 
cially age the wine. This tends to decrease the number of 
germs that would be injurious in fermentation. The addi- 
tion of cane sugar, called " chaptalising " in France, is 
practiced, under certain very carefully guarded conditions, 
to increase the yield of alcohol, and commercial glucose is 
used in the same way. In Germany the addition of sugar 
to " musts " deficient in this material is permitted. A 
cheap wine is sometimes put upon the market which con- 
tains no juice of the grape whatever, but is made from cider 
as a basis, to which is added alcohol, tannin, glycerin, 
glucose, cream of tartar, orris root, ethereal oils, and fre- 
quently oenanthic ether. An extract is frequently made 
from raisins, which is colored and flavored to imitate wine. 

Wine is subject to numerous diseases, such as souring, 
ropiness, bitterness, and molding. Poor wines or those 
that have deteriorated are sometimes distilled to make 
brandy. 

The total wine production of the world in 1913 was 
nearly 4,000,000,000 gallons, only one one-hundredth of 
which was produced in the United States. 

Experiment 175. Test a small portion of wine or grape juice 
in a test tube for grape sugar, by the Fehling test. 

Experiment 176. Evaporate 10 cc. of wine or grape juice 
to one half its volume on a water bath, and to the solution add 
50 cc. of a mixture of alcohol and ether. Put this solution in a 
flask and allow to stand tightly corked for some time, and notice 
the acid potassium tartrate which crystallizes out. 

* Experiment 177. Acidify a sample of wine with hydro- 
chloric acid, heat to boiling, and add a few drops of barium 
chlorid. If there is more than a trace of barium sulfate, " plas- 
tering " of the wine is indicated. Normal wine does not con- 
tain over .06 % of sulfuric acid calculated as potassium sulfate. 



ALCOHOLIC BEVERAGES 335 

CIDER 

The fresh juice of the apple, known as sweet cider, is a 
very convenient solution for growth of the yeast Saccha- 
romyces apiculatus, which starts fermentation, and so cider 
does not long remain sweet. The crushed apples are 
pressed in a cider press, and the juice is then run off into 
barrels and allowed to ferment. The refuse left after the 
juice has been expressed is called " pomace/' and is utilized 
in some other industries. (See p. 270.) In some coun- 
tries more care is used in the preparation of this beverage, 
and it is clarified by the use of gelatin and racked off or 
filtered from the deposited matter. This process tends 
to improve the quality of the cider. 

Cider contains from 3 to 7% of alcohol by volume, 
besides malic acid, sugar, extractives, and mineral salts. 

ADULTERATION AND FALSIFICATION OF CIDER 

There are found on the market samples of cider made by 
adding water to the pomace, and repressing ; but this cider 
is more frequently used as a basis for the manufacture of 
other beverages. The most important sophistications of 
cider are water, sugar, and especially the use of preserva- 
tives. The preservatives most commonly used are benzoic 
acid, salicylic acid, sulfurous acid or sodium sulfite, and 
betanaphthol. Mustard seeds, borax, and horse radish are 
also used. From some experiments by the author x it was 
shown that the effect of those substances is to retard the 
fermentation, and not to ultimately prevent it. It is prob- 
ably true that substances that will retard fermentation will 
also have a tendency to produce indigestion. 2 (See Chap- 
ter XXVII.) 

1 Kan. Univ. Quar., VI, A, p. 111. 

2 Shepard, Report, Ohio Food Commis., 1904. 



336 SANITARY AND APPLIED CHEMISTRY 

Perry, or pear cider, is made and consumed more exten- 
sively abroad than in the United States. It does not differ 
essentially except in flavor from cider. 

Experiment 178. To test for salicylic acid in cider or beer, 
acidulate a sample with sulfuric acid and shake with a mixture 
of equal parts of ether and petroleum naphtha. Remove the 
ethereal layer with a pipette and allow to evaporate to small 
volume on a watch glass. Add a little water and a few drops 
of ferric chlorid solution, when the presence of salicylic acid 
will be indicated by a violet color. 

BEER 

This beverage is a representative of malt liquors. 
According to the best authorities, genuine beer should be 
made from malt, starchy material, hops, yeast, and water, 
and nothing else. Malt is made by soaking barley in 
water for several days, then piling it up on the floor or 
" couching " till it sprouts and the little radical starts to 
grow; then the process of germination is retarded by 
" flooring/' as it is called ; i.e. spreading in progressively 
thinner and thinner layers upon the floor, and germination 
is finally stopped by drying the grain. The color of the 
malt depends upon the temperature at which this drying 
is conducted. If dried between 32° and 37° C, it forms a 
" pale malt " ; if from 38° to 50°, a brown malt. In the 
process of malting the albuminous substances of the grain 
are changed in part to diastase, an active ferment, which 
has the peculiar property of changing starch to dextrin 
and then to sugar (maltose). One part of diastase under 
favorable conditions will convert 2000 parts of starch to 
sugar. 

The next process is known as " mashing/' This consists 
in grinding the malt and soaking it in water at a tempera- 



ALCOHOLIC BEVERAGES 



337 



ture of 75° C. The change from starch to sugar is still 
more completely effected here. The clear infusion, called 
the " wort," is boiled with hops, and the solution is cooled 
very rapidly to 18° C. Yeast is added, in the proportion 
of about 1 gal. to 100 gal. of wort, and the liquid is allowed 
to ferment about 8 days. It is then drawn off into settling 
tanks and finally into casks, and stored in a cool place to 
ripen. The yeast changes the sugar into alcohol and 
carbon dioxid, in accordance with the reaction : — 
C 6 H 12 6 = 2 C0 2 + 2 C 2 H 5 OH. 

The sugar is not completely eliminated, as that would 
interfere with the agreeable taste. 

The following analyses of malt liquors, taken from 
various sources, will give an idea of their composition : — 



Milwaukee lager, bottled 

H. export 

Philadelphia ale, bottled . 

Pilsen lager 

Munich 

Schenk 

Lager (beer) 

Export beer 

Bock beer 

Weiss beer 

Dublin stout, XXX . . 

Porter 

Ale 

Burton bitter ale . . . 



1.0100 
1.0178 
1.0059 



1.0114 
1.0162 
1.0176 
1.0213 
1.0137 



1.0191 
1.0141 



85.85 
91.11 
90.08 
89.01 
87.87 
91.63 

88.49 
89.42 



pq 



5.35 
5.50 
7.75 
4.10 
5.75 
4.20 
4.90 
5.50 
5.85 
3.40 
8.45 
5.90 
5.95 
6.80 



4.18 
6.15 
3.46 
4.22 
9.40 
5.34 
5.79 
6.38 
7.21 
5.43 
9.52 
6.59 
5.65 
5.42 






1.10 

2.14 

.59 



.95 
.88 
1.20 
1.81 
1.62 
5.35 
2.62 
1.07 
1.62 



§5 



1.57 

2.54 

.90 

2.65 

3.11 
3.73 
3.47 
3.97 
2.42 
2.09 
3.08 
1.81 
2.60 



3g 

as 



.20 
.31 

.40 



.20 
.23 
.25 
.26 
.15 

.36 
.31 



The quality of the beer depends upon the manner of 
brewing, the temperature, qualities of ingredients, method 
of storing, kind of water used, quality of the yeast, whether 



338 SANITARY AND APPLIED CHEMISTRY 

" top yeast " or " bottom yeast/' and the temperature at 
which it is stored. The lager beer proper, or store beer, 
should be kept in a cool place for several months before 
being used. Very much of the beer in use in the United 
States is what is known as " present use " beer. Bock 
beer is a strong variety of beer made for use in the spring 
only, and Weiss beer is a very weak beverage used in 
Germany. Ale, porter, and stout are richer in alcohol 
than lager beer. 

In the manufacture of beer the tendency is to use as little 
of expensive ingredients as possible, so in cheap beers, 
part, or all, of the barley malt is replaced by some other 
grain, as corn or rye, and even a special kind of glucose is 
added to furnish a material that will readily ferment. It is 
asserted that sometimes the bitter principle in cheap beer 
is also replaced by quassia and other bitter substances. 
Most of the beer on the market contains from 2 to 5 % of 
alcohol by volume. There are comparatively few adul- 
terations in beer except those mentioned. Salicylic acid 
is, however, frequently used as a preservative. A kind of 
so-called beer has been put upon the market in some prohi- 
bition localities. This often contains less than 2% of 
alcohol, and is sold under a variety of special names. It 
is frequently made in the same way as beer, and the alcohol 
is expelled by heat. 

Sake, the favorite beverage of the Japanese, is prepared 
from rice fermented by the use of a peculiar fungus 
grown for that purpose. It contains about 12.5% of 
alcohol. 1 

" Small beer," made by the use of sugar or molasses, 
and yeast with some flavor, contains from 0.3 % to 2 % of 
alcohol. 

i Church, "Food," p. 195. 



ALCOHOLIC BEVEEAGES 339 

Experiment 179. To show the presence of alcohol in a 
sample of wine, beer, or cider, heat about 100 cc. in a 500 cc. 
flask, into the neck of which is fitted the large end of a cal- 
cium chlorid tube. As soon as the liquid begins to boil slowly, 
light the vapor that escapes at the top, and observe that it burns 
with a characteristic alcohol flame. 

Experiment 180. Collect some of the distillate from a sam- 
ple of malt or fermented liquor, by boiling it very gently in a 
500 cc. flask, to which is fitted, by a perforated cork, a glass tube 
about 60 cm. long, bent at an acute angle above the cork. At 
the other end of the glass tube place a small flask or test tube 
surrounded by cold water. The alcohol will condense in the 
cooled flask. 

Experiment 181. Test some of the alcohol, first by taste, 
second, by burning, third, by adding to a sample about 1 g. 
solid NaOH and a few crystals of iodin. The formation of a 
yellowish crystalline precipitate of iodoform, CHI3, which has a 
characteristic odor, indicates the presence of alcohol in the 
distillate. 

DISTILLED LIQUORS 

Distilled liquors, such as rum, gin, brandy, and whisky, 
are made from some saccharine substance like molasses, or 
some starchy substance like corn, rye, barley, or rice. The 
chemical action in the case of starch is first to change the 
starch by the addition of ground malt to sugar, which is 
then decomposed in the process of fermentation with 
yeast, into alcohol and carbon dioxid. Diastase, which is 
present in the malt, is the active agent in transforming the 
starch to sugar. This sugar is principally maltose, mixed 
with one of the dextrins. 1 After fermentation the alcohol 
is distilled off, and with it some other volatile substances, 
especially ethers, which give the characteristic odor and 
taste to the liquor. 

1 Jago, '"The Science and Art of Bread Making," p. 126. 



340 SANITARY AND APPLIED CHEMISTRY 

Originally the liquid actually distilled over was used 
directly as a beverage. This was about of proof strength, 
and had the characteristic flavor of the substance from 
which it was distilled. Practically, at the present time, a 
large proportion of the liquor on the market is made by 
the rectifiers, using as a basis pure alcohol and " high 
wines," which are diluted, colored, and flavored to imitate 
the required beverage. 

The method used in making alcohol is to prepare what 
is called the mash by crushing the grain and other starchy 
material into a fine pulp, and soaking it with water, cooling 
it quickly, and allowing it to ferment with yeast. Some- 
times the mash is made by the use of sulfuric acid, thus 
converting the starch directly into dextrin. The mash, 
after fermentation, is distilled in an apparatus so arranged 
that the alcohol, as it is volatilized, shall be quickly cooled 
and condensed in a coiled pipe. Theoretically, — 
100 parts of starch yield 56.78 parts of alcohol, 
100 parts of cane sugar yield 53.08 parts of alcohol, 
100 parts of dextrin yield 51.01 parts of alcohol, 
but practically this output is not reached. 

The last part of the distillate usually contains more of 
the higher alcohols of the series, especially amyl alcohol, 
which is one of the constituents of " fusel oil." This is 
considered one of the most injurious ingredients in ordi- 
nary liquors. 

Brandy should be made by the distillation of wine, 
and should obtain its odor and flavor from the fer- 
mented juice of the grape. In actual practice in the 
hands of the rectifier, it is often made from alcohol di- 
luted, colored with caramel, and flavored with oil of 
cognac, which is distilled from the marc or refuse from 
the manufacture of wine. The flavor of brandy is much 



ALCOHOLIC BEVERAGES 341 

improved by age, but many processes of artificial aging 
have been devised. 

* Whisky, as originally made from corn, barley, or pota- 
toes, had a brownish color, and a peaty or smoky flavor 
that was imparted to it by the smoke of the peat fires 
used in its manufacture in Scotland and Ireland. This 
flavor is now imparted to the commercial article by the 
use of creosote or some similar compound. 

Rum was originally made in the West Indies from 
residue left after the manufacture of cane sugar or from 
molasses, and the peculiar flavor it possessed was produced 
by the volatile oils that are developed in the manufacture 
of sugar from cane juice. Much of it is now manufactured 
by the " rectifier " in the ways already described. 

Gin was originally made by the distillation of an alco- 
holic liquid with juniper berries, but at present the rectifier 
adds to the diluted alcohol, oil of juniper or turpentine, or 
both, some aromatic seeds and fruits, and redistills the 
mixture. Many roots and drugs are frequently added to 
improve the flavor of gin. 

Experiment 182. Alcohol may be made from the fermen- 
tation of a saccharine liquid, as follows : In a 2-liter flask mix 
60 cc. of molasses with 700 cc. of water, and add a small amount 
of yeast, and set aside in a warm place for a day or two. When 
the mass foams and carbon dioxid is freely given off, distill 
slowly by attaching a condenser, or a cork, through which passes 
a long tube bent to an acute angle, as in Experiment 180. Exam- 
ine the distillate by taste and smell, and by the test mentioned 
in Experiment 181. 

ADULTERATION OF LIQUORS 

The most prevalent form of sophistication with brandy, 
rum, and gin is the artificial imitations, and the direct 
addition of substances injurious to health is of infrequent 



342 SANITARY AND APPLIED CHEMISTRY 

occurrence. The most dangerous ingredient in the fic- 
titious product is supposed to be the fusel oil, which is a 
mixture of the higher alcohols, but some authorities have 
made experiments with this substance, and find no injurious 
effect, even when considerable quantities mixed with 
whisky are taken for quite a length of time. It is suggested 
that perhaps the compounds which make some spirits, espe- 
cially those which are recently distilled, or " raw," more 
injurious than those which are " aged," may be other 
by-products of fermentation, such as furfurol. 

LIQUEURS OR CORDIALS 

These beverages consist of very strong alcohol, flavored 
with aromatic substances, and often highly colored with a 
coal tar or a vegetable coloring matter. Absinthe, the 
most important of these, is yellowish green in color, and 
contains oil of wormwood, a substance that has a very 
injurious effect on the nervous system, with anise, sweet 
flag, cloves, angelica, and peppermint. This liqueur 
usually contains over 50 % of alcohol. 

Other beverages of this class are maraschino, distilled 
originally from the sour Italian cherry; chartreuse and 
benedictine, named from the monasteries where they were 
originally made ; kummel ; curagao, made from the rind 
of bitter oranges ; ratafia, made in France from fruits ; 
angostura and vermuth. Nearly all these contain a 
large amount of sugar and a high per cent of alcohol, and 
are flavored with various essential oils, herbs, and spices. 

PHYSIOLOGICAL ACTION OF ALCOHOL 

The question as to whether alcohol is, properly speaking, 
a food, or whether it simply acts as a stimulating beverage, 



ALCOHOLIC BEVERAGES 343 

is one that has occasioned a vast amount of discussion. 
The best authorities seem to agree that there are cases 
of disease in which it is the most useful material that can 
be administered. Professor At water, who has investigated 
the action of alcohol in his respiration calorimeter, speak- 
ing of its use in disease, says : " What is wanted is a 
material which will not have to be digested and can be 
easily absorbed, is readily oxidized, and will supply the 
requisite energy. I know of no other material which 
would seem to meet these requirements so naturally and 
so fully as alcohol. It does not require digestion, is 
absorbed by the stomach and presumably by the intestines, 
with great ease. Outside the body it is oxidized very 
readily, within the body it appears to be quickly burned, 
and it supplies a large amount of energy/ ' From one fifth 
to one seventh of the total calories of the diet may be 
replaced by alcohol. 

The same author says of the results of his experiments, 
that he found that " the alcohol was almost completely 
oxidized. The kinetic energy resulting from that oxida- 
tion agrees very closely with the potential energy of the 
same amount of alcohol as measured by its heat of combus- 
tion as determined by the bomb calorimeter, and the alcohol 
served to protect body protein and fat from oxidation/ ' 
Alcohol is inferior to carbohydrates, however, to protect 
protein of the body from oxidation. 1 As a stimulant, 
alcohol acts primarily upon the nervous system and the 
circulation, and quickens the transmission and enhances 
the effect of nerve currents. Although alcohol tends to 
remove muscular fatigue and to increase the force of 
muscular action, yet its use is absolutely forbidden to 

1 See also "Food in Health and Disease," Davis, 2d edition, p. 135. 
Thompson, "Practical Dietetics," p. 229. 



344 SANITARY AND APPLIED CHEMISTRY 

athletes in training, and soldiers in the army continue in 
better health if they entirely abstain from the use of this 
substance. 

It will be seen that although alcohol has some right to be 
regarded as food, yet it is not a food of any practical im- 
portance, for it can merely replace a certain amount of the 
fat, and perhaps of the carbohydrates, in the body, while 
its secondary effects on the nervous and vascular systems 
counteract, to a large extent, the benefits derived from the 
production of heat and energy by its oxidation. 1 

1 Hutchison, "Food and Dietetics.'* 



CHAPTER XXVI 
FOOD ACCESSORIES 

A large number of aromatic substances, which have no 
direct food value, are prized for the agreeable flavor which 
they impart to food. Condiments are by some writers 
defined as the substances eaten with meat and used with 
salt, while the term spices is restricted to those substances 
which are used with sugar. It is, however, impossible to 
draw a definite line between the two classes of substances. 

The spices, since they are used only in small quantities 
and are quite expensive, readily lend themselves to all 
kinds of falsification and adulteration. 

The adulterants are usually of a harmless character, 
and consist of English walnut shells, Brazil nut shells, 
almond shells, cocoanut shells, date stones, sawdust, 
linseed meal, cocoa shells, red sandalwood, Egyptian corn, 
rice flour, ground crackers, or "hard tack/ 7 bran, and many 
other by-products from milling, plaster, corn meal, 
turmeric, cottonseed meal, olive stones, and pea meal. 1 

Since the better enforcement of the Pure Food Laws by 
Federal and State Authorities the adulteration of spices 
has been almost eliminated. 

In most cases these fraudulent mixtures can be detected 
only by the skilled chemist or microscopist, so the only 
safeguard of the housekeeper is to buy of reliable dealers, 
get the goods in sealed packages, and to pay a fair price. 

i Rep. Conn. Agric. Exp. Station, 1898-1904. 
345 



346 SANITARY AND APPLIED CHEMISTRY 

In most cases it is safer to buy the unground spice. A 
brief account only of the source and properties of the most 
important products will be given. 

Cloves are the dried flower buds of a plant belonging to 
the Myrtle family, growing in Ceylon, Brazil, India, the 
East Indies, and Zanzibar. The tree, which is an ever- 
green, is usually less than 40 ft. high. After the buds are 
picked they are laid in the sun to dry. The volatile oil 
of cloves, which may be distilled off with water, contains 
about 70 % of eugenol, CioHi 2 2 . In addition to the use 
of the clove " stock " above mentioned, " exhausted " 
cloves, both whole and powdered, — that is, those which 
have been deprived of a portion of their volatile oil, — are 
put upon the market and mixed with fresh cloves, so that 
the fraud shall be less apparent. 

Experiment 183. Grind about 15 grams of cloves in a 
porcelain mortar and introduce into a liter retort with water 
and boil for some time, condensing the steam in a flask floating 
in a pan of water. Pour the distillate into a tall tube and allow 
it to stand, and the oil of cloves will rise to the surface. 

Cinnamon is the inner bark of a tree of the Laurel 
family, which is cultivated in Ceylon, Java, Sumatra, and 
adjacent countries. A cheaper and more common cassia 
which is also commercially known as cinnamon, comes 
from another tree of the Laurel family, which grows 
in China and India. Cassia buds, the dried flower of the 
China cassia, are also upon the market. The odor of 
cinnamon is due to the presence of a volatile oil, which 
consists principally of cinnamic aldehyde, C 6 HbCH : 
CH.CHO. A " stock " colored with red sandalwood is 
commonly used as an adulterant ; this stock frequently 
consists largely of foreign barks, such as that of the elm. 



FOOD ACCESSORIES 347 

Pepper is the dried berry of the Piper nigrum, a climbing 
plant which grows in tropical countries. For preparing 
black pepper the unripe fruit is dried in the sun, but to 
prepare the white pepper the ripe fruit is soaked in water 
and the skins are removed by friction. The taste and 
odor of pepper is due to the presence of an essential oil, a 
hydrocarbon, having the formula Ci Hi 8 , and another im- 
portant substance called piperin, C17H19NO3. In addition 
to the ordinary adulterants in ground pepper, Egyptian 
corn and " long pepper " are used, while cayenne pepper is 
often added to raise the pungency nearer to that of the 
pure product. 

Ginger is the rhizome of the Zingiber officinale, an annual 
herb which is a native of India and China, and is culti- 
vated in the West Indies, Africa, and Australia. Black 
ginger is prepared by scalding the freshly dug root, and 
drying immediately. White, or " scraped/ ' ginger is the 
same material that has been scraped and sometimes further 
whitened by treatment with some bleaching age,nt. Pre- 
served ginger is prepared by boiling the root and curing 
with sugar. A volatile oil and a pungent resin give to 
ginger its characteristic odor and taste. Ginger is often 
adulterated by mixing with it ginger roots that have been 
exhausted with alcohol. The alcoholic extract or water 
extract is used for the manufacture of ginger ale. 

Nutmeg and mace occur in the fruit of trees of the Myris- 
tica family, which grow especially in the Malay Peninsula. 
The tree grows from 20 to 30 ft. high, and produces flowers 
after about the eighth year. The fruit is surrounded by a 
fleshy crimson covering, which when dried furnishes the 
mace of commerce, and the hard seed the nutmeg. This is 
further prepared by washing with milk of lime. Nutmegs 
contain from 3 to 5% of a volatile oil. As the whole nut- 



348 SANITARY AND APPLIED CHEMISTRY 

meg is used by the cook, rather than a ground product, 
there is not much opportunity for adulteration. Mace has 
the usual adulterants, and frequently a wild mace, known 
as Bombay mace, which is practically without taste is 
added. 

White mustard is the seed of the Sinapis alba, and black 
mustard that of the Sinapis nigra. The plant, which is 
an herb, having yellow flowers, grows both in the United 
States and in Europe. Both varieties contain about 35% 
of a fixed oil, which can be separated by heat and pressure, 
a soluble ferment called myrosin, and sulfocyanate of sina- 
pin, C16H23NO5. The black mustard contains potassium 
myronate, which, when moistened with water, forms the 
volatile oil of black mustard, known to the chemist as 
allyl isothyocyanate, C3H5CSN. This has a strong mus- 
tard-like odor, and the vapor excites tears. This oil pro- 
duces blisters on the skin, and hence the use of the so- 
called " mustard plaster." The chief adulterants of 
ground mustard are wheat, flour or starch, mustard 
hulls, and turmeric to restore the yellow color lost by the 
adulteration with a starch powder. Sometimes cayenne 
pepper is also added to restore the pungency. 

VINEGAR 

Since most of the vinegar of commerce is used in connec- 
tion with spices and in the preparation of pickles, etc., 
its properties may be studied in this connection. Vinegar 
is dilute acetic acid, C2H4O2, flavored with the fruit ethers, 
and can be made from any dilute alcoholic liquor. The 
whole process of the conversion of cane sugar to vinegar 
would be represented by the equations, — 

C12H22O11 + H2O = 2 C6H12O6 ; 

Gane Sugar Invert Sugar 



POOD ACCESSOEIES 349 

CaHuOe = 2 C 2 H 5 OH + 2 C0 2 ; 

Alcohol 

C 2 H 6 OH + O = C 2 H 4 + H 2 ; 

Aldehyde 

C 2 H 4 + O = C 2 H 4 2 . 

Acetic Acid 

The change from alcohol to vinegar is brought about by 
the ferment mycoderma aceti, found in the " mother." The 
conditions for this fermentation are an alcoholic liquid con- 
taining not over 12 % of alcohol, an abundance of air, a 
temperature of from 20° to 35° C, and the presence of the 
ferment. 

The materials used are (1) wine; (2) other fermented 
fruit juices ; (3) spirits like diluted whisky, or residues 
from the manufacture of sugar ; (4) malt wort, or beer ; 
(5) sugar beets. There are several processes used for the 
manufacture of vinegar on a large scale, in addition to the 
usual process of allowing the cider to ferment in an ordi- 
nary barrel in a warm cellar with the bunghole left open 
for two or three years. From 100 lb. of apples the ordi- 
nary yield ig 7 gallons of cider. 

QUICK PROCESS VINEGAR 

In France and Germany vinegar is made from wine by 
pouring it from time to time into an oaken vessel which has 
been soaked with boiling vinegar, and then siphoning off 
into storage tanks. The " mother casks " are used for 
a long time, until they contain a large amount of argols, 
ferment, etc. *-** ^ 

Another method is by the " quick vinegar process," 
which was introduced by Schutzenbach in 1823, and is quite 
extensively used for spirit vinegar in Germany and the 
United States, and for malt vinegar in England. 



350 SANITARY AND APPLIED CHEMISTRY 

In this process, an upright cask about 10 ft. high, and 
provided with a perforated false bottom about a foot above 
the true bottom, is filled with beech or oak shavings. Just 
under the false bottom a series of holes slanting downward 
is bored entirely around the cask. The shavings are 
soaked in warm vinegar, and covered by a wooden disk 
perforated with numerous holes, through which cords are 
loosely drawn. There are also several glass tubes extend- 
ing through this disk to assist in the circulation of the air. 
After covering the cask with a wooden cover having a 
hole in the center, the dilute alcoholic liquor is poured into 
the upper compartment and slowly trickles over the shav- 
ings. 

As the process of oxidation proceeds, considerable heat 
is developed, and this causes an upward current of air 
which enters the cask below the false bottom, and escapes 
to the upper part through the glass tubes. By a siphon 
the partially acetified liquid is drawn off into a second cask. 
With 4 % of alcohol in the original liquid, good vinegar will 
be drawn from the second vat. If " vinegar eels " appear, 
the converting cask is treated with vinegar so hot that 
when drawn out it has a temperature of 50° C, which 
kills the eels. When spirit is used in this process, a little 
infusion of malt is added to furnish organic matter suffi- 
cient for the growth of the ferment. 

Wine vinegar may be red or yellowish in color, and con- 
tains from 6 to 9 % of absolute acetic acid. Beer and 
malt vinegars are higher in specific gravity than wine 
vinegar, and contain considerable extractive matter, and 
from 3 to 6 % of acetic acid. Cider vinegar has the odor of 
apples, and when evaporated yields an extract that smells 
and tastes like baked apples. It contains malic acid and 
from 3^ to 6 % of acetic acid. The acidity should never 



FOOD ACCESSORIES 351 

be below 4 % and the specific gravity should never be 
less than 1.015. The strength of vinegar is often esti- 
mated in " grains " ; thus a "40 grain " vinegar would con- 
tain 4 per cent of acetic acid. 

Imitation vinegars are sometimes made by the use of 
acetic acid distilled from wood, and flavored with acetic 
ether and colored with caramel. The extract from this 
imitation vinegar differs from malt vinegar in not contain- 
ing phosphate, and from wine vinegar in the absence of 
tartaric acid, and from cider vinegar in the absence of 
malic acid. 

The acidity of vinegar assists in the softening of some 
foods, such as beets, cabbage, cucumbers, hard-boiled 
eggs, corned beef, and lobsters, but it should not be used 
in excess on account of its tendency to cause anemia and 
emaciation. 

Experiment 184. The approximate acidity of a sample of 
vinegar may be ascertained by the use of saturated limewater. 
This is made by allowing water to stand for some time with 
frequent shaking over slaked lime. The strength of the clear 

liquid which is drawn off is very nearly normal. To test 

the vinegar, 2.75 cc. are placed in a small Erlenmeyer flask with 
some water, and a few drops of phenolphthalein as an indicator, 
and titrated with limewater contained in a burette. When 
the pinkish color shows that the free acid has been neutralized, 
read the number of cubic centimeters of limewater used, and 
divide this by 10. This gives the percentage of acid in the 
vinegar. 

Experiment 185. To detect a free mineral acid in vinegar, 
add to 5 cc. of vinegar 5 or 10 cc. of water ; after mixing well, 
add 4 or 5 drops of an aqueous solution of methyl-violet (one 
part of methyl- violet 2 B in 10,000 parts of water). The occur- 
rence of a blue or green color indicates a mineral acid. 1 

1 Bui. 65, U. S. Dept. Agric, Bu. Chem., p. 64. 



352 SANITARY AND APPLIED CHEMISTRY 

Experiment 186. Caramel is often used to color imitation 
vinegars. To detect this, place about 25 cc. of the sample in 
a large test tube or in a bottle, and add to it about 10 grams 
of fuller's earth, shake the sample vigorously for several minutes, 
and filter. The first portion of the liquid which passes through 
the filter should be filtered again. Return the filtered sample 
to original tube, and compare the color of this solution in a 
similar tube with that of an equal quantity of vinegar that has 
not been treated. If the treated sample is considerably lighter 
in color than that which has not been treated, the vinegar is 
probably colored with caramel. Caramel occurs naturally in 
malt vinegar. 1 

Experiment 187. To obtain the acetic acid of vinegar 
free from extractive matter, pour 250 cc. of vinegar into a 
flask, add to it 25 cc. of dilute sulfuric acid, and distill by the 
use of the simple apparatus described in Experiment 180. 
Collect the distillate in a flask and examine its odor, taste, etc. 

SALT 

Common salt, NaCl, has been used for thousands of 
years as an essential ingredient of foods, and as a preserva- 
tive. Fortunately, it is found in numerous localities all 
over the world. In the United States, the chief salt- 
producing localities are Michigan, New York, Kansas, 
Louisiana, and Ohio, which together furnish about 90 % 
of the total output, 2 and smaller quantities are obtained 
from California, Utah, West Virginia, Oklahoma, Texas, 
and Pennsylvania. 

Salt is obtained either as rock salt, which is mined in 
several localities, by the evaporation of sea water or that 
of salt lakes, or by the evaporation of brine, which is 
obtained from salt wells or borings into the salt bed. Most 
of the table salt of commerce is made by the latter process. 

i Bui. 100, U. S. Dept. Agric, Bu. Chem., p. 48. 

2 Bailey, International Congress of Applied Chemistry, Berlin, 1903. 



FOOD ACCESSORIES 353 

In some localities solar evaporation is relied upon for con- 
centration of the brine, but usually the brine is heated in 
an open pan by direct heat or in a " Grainer " by steam 
heat. Many producers are introducing cement evaporat- 
ing pans, automatic self-acting rakers, and vacuum pans. 
The brine when pumped from the wells contains some 
impurities, and these, especially the calcium sulfate, are 
deposited when the brine is first concentrated, so that in 
this way the brine can be partially purified in the first pan, 
before it is run into the evaporating pans proper. The 
composition of a good brand of salt is as follows : — 

Pee Cent 

Sodium chlorid 97.75 

Insoluble residue .03 

Calcium sulfate 1.84 

Magnesium chlorid .38 

Total 100.00 

Most of the salts on the market contain from 97 to 99 % 
of pure salt. When salt absorbs moisture, it becomes hard 
and inconvenient for domestic use. This is sometimes 
remedied by the addition of a small quantity of starch or 
magnesium carbonate. 



2a 



CHAPTER XXVII 
PRESERVATION OF FOOD 

It is only within the last hundred years that any ade- 
quate methods for the preservation of food have been 
devised ; in fact, within the last fifty years the greatest 
advances have been made in this art. Formerly, fruits, 
vegetables, and meats must be consumed in the locality 
where they were produced, and fruits especially must be 
used as soon as ripe. In 1804 M. Appert of Paris found 
that meat and other organic substances would keep indef- 
initely if sealed and then heated in boiling water. In 
1810 he suggested the method of introducing steam and 
heating, and then sealing, so that when the vessel cooled 
a vacuum was formed. 

By the use of modern methods of preservation the season 
for the use of each fruit has been extended ; and the prod- 
uct of one climate can be transported to another climate 
for consumption. Meats and vegetables can be preserved 
for months, and so the variety of food for man has been 
greatly increased. Since the fermentative changes that 
take place when food is kept for some time are due to the 
growth of various microorganisms, any process which 
will prevent this growth or keep these organisms out of 
the food will assist in its preservation. Warmth, moisture, 
and access of germ-laden air are conditions favorable for 
the decomposition of food. 

Some of the methods adopted for the preservation of 

354 



PRESERVATION OF FOOD 355 

food are (1) maintaining a low temperature ; (2) drying 
so as to remove as much moisture as possible ; (3) addition 
of sugar or glucose ; (4) the use of saltpeter or brine ; (5) 
pickling with vinegar ; (6) canning or placing in a sterilized 
atmosphere; (7) the use of chemical preservatives. 

Fermentation and decay take place best at a moderately 
high temperature, so cold storage is introduced not only to 
transport fruits and meats from one section of the country 
to another, but also to keep the food from the season when 
it is abundant until the season when it is scarce. Preserva- 
tion by the use of salt, smoke, sugar, saltpeter, or vinegar 
furnishes conditions unfavorable to the growth of micro- 
organisms, and so decay is prevented. Dried or " jerked " 
meat will keep a long time for the same reason, especially 
in a dry climate. 

In smoking the meat, which is usually previously salted, 
it is dried and penetrated by acetic acid, creosote, and 
other preservatives of the smoke. 

In " quick smoking " processes the meat is dipped 
several times in a solution of pyroligneous acid (which is 
made by the distillation of wood) and dried in the air. 
Other chemicals are frequently used. 

The process of food preservation by canning or protect- 
ing from air and sterilizing has developed to an enormous 
extent in the United States. When we consider the annual 
output of 238,000,000 cans of corn, 212,000,000 cans of peas, 
and 388,000,000 cans of tomatoes, besides millions of cans 
of other vegetables and fruits, some idea of the value of 
this process to the human race is obtained. 

Fortunately, too, most of this food is prepared in 
such a way as to be entirely wholesome. The ob- 
ject to be attained in canning is to destroy the micro- 
organisms of various kinds, so it makes no special differ- 



356 SANITARY AND APPLIED CHEMISTRY 

ence whether a little air remains in the can or not, as long 
as the contents is perfectly sterilized, although formerly 
it was held that all the air must be excluded. 

In domestic practice, fruit may be preserved by packing 
in glass cans, filling nearly full of water, adding some sugar 
if desired, and then immersing the cans nearly to the neck 
in a vessel of cold water. The water is heated to boiling, 
and allow to boil from 15 to 30 min., dependent on the 
size of the fruit, and then the cans are removed from the 
water and immediately sealed. This process has the ad- 
vantage of preserving the fruit whole and unbroken. 

Another method much in vogue is to cook the fruit or 
vegetables, then put them, while still hot, in glass or tin 
cans that have just been taken out of boiling water, and to 
seal immediately with the ordinary glass cover and rubber 
washer or with cork and sealing wax. 

The method used at canning factories is, in general, to 
pack the material in tin cans, with the required amount of 
water, and after sealing to cook with hot water or steam. 
The cans are then punctured to allow the excess of air to 
escape, again sealed with a drop of solder, and again heated 
for some time to destroy all microorganisms. 

A more modern method of canning is to cook the fruit 
at a temperature of 82° to 88° C. before transferring to the 
cans, and afterward heat in the cans, when sealed, to a 
temperature of about 125° C. in dry air retorts, so that it 
shall be completely sterilized. 1 This process can be fin- 
ished in a shorter time than the former, and on account of 
the higher temperature employed is very effective. 

Experiment 188. To show the effect of exclusion of ordi- 
nary air from fruit, prepare two samples thus: Place some 
hot apple sauce in two 250 cc. bottles that have just been heated 

1 "Food Inspection and Analysis," Leach, 3d ed., p. 901. 



PRESERVATION OF FOOD 357 

with boiling water. In the mouth of one bottle place a per- 
forated cork, through the opening of which passes a calcium 
chlorid tube packed with cotton, that has been heated in an 
oven to 120° C. In the mouth of the other bottle place a cork 
having a small opening in it. Allow these bottles to stand for 
a week or more in a warm place, and notice the almost entire 
absence of mold in the bottle which is protected from the micro- 
organisms of the air by the cotton, and the abundant mold on 
the surface of the sauce in the other bottle. 

When canned food spoils if put up in tin cans, the 
can usually becomes convex on the ends, instead of con- 
cave, as it is found normally, on account of the generation 
of gases by fermentation. Formerly it was not an un- 
common practice for manufacturers to puncture these 
"swells" and reheat them to stop fermentation, and after- 
ward solder them again, and put them on the market. 

Since tin cans are used in the preservation of food, and 
as the tin plate, from which the cans are made, often 
contains considerable lead, it is not uncommon to find salts 
of tin, iron, and lead in the canned products. This is 
partly due to carelessness in soldering of the cans, and 
allowing the drops of the solder, which may contain 50 % 
of lead, to remain inside the can, and partly because the 
acid fruits act on the tin plate of which the can is composed. 

Formerly very grave danger was apprehended from the 
metals that might be contained in canned goods, but 
the fact is that we have not experimentally proven whether 
the small quantities that are found have a poisonous effect 
or not. 

Experiment 189. To show the presence of iron in canned 
fruit, test some of the juice from a " swell " can of California 
grapes or other fruit (better one that has been canned for some 
time) with a little of a strong infusion of tea. Since the tea 



358 SANITARY AND APPLIED CHEMISTRY 

contains tannic acid (Experiment 172) it will form a black color- 
ation (ink) with the iron that has been dissolved from the tin 
plate by the acid of the fruit. 

CHEMICAL PRESERVATIVES 

In recent years the practice of adding preservatives to 
food has greatly increased. These preserve the foods by 
preventing the growth of bacteria. There may be a differ- 
ence of opinion in regard to the use of some of them, but it 
seems perfectly reasonable that antiseptic substances 
which will prevent the decay of food will be liable also to 
retard the digestive processes. Food that has really 
begun to decay may, it is by some asserted, by the use 
of these preservatives, be put on the market and sold as 
wholesome. It is no defense of the practice to claim that 
food that has been thus treated is better than if it had not 
been treated, for such food, which has begun to decay or 
ferment, should be condemned without question. 

When preservatives are added to food intended for the 
use of invalids and young children, they are especially 
liable to interfere with the digestion and prove injurious 
to the system. Many tests have been made upon the 
lower animals, and some results have been obtained which 
indicate that some preservatives may be used with impu- 
nity, but the time has not come to admit the use of preserv- 
atives in foods without question. This position has been 
taken by the health authorities in many states ; and where 
the use of these substances is not actually prohibited, they 
require at least that each package so preserved shall be 
labeled to that effect. 

Dr. Vaughan l says, " A true food preservative must 
keep the substance to which it is added in a wholesome 

* Jour. Am. Med. Assoc, Vol. XLIV, p. 753. 



PRESERVATION OF FOOD 359 

condition so that it can be consumed by persons in every 
physical condition of life without impairment of health or 
danger of life. It is not the function of a food preservative 
to impart to the food a deceptive appearance and to 
make it look better than it actually is. The law . . . 
forbids the use of all meat preservatives that restore 
the color and fresh appearance to partially decom- 
posed meats. ... To prevent the development of 
those bacteria that produce odoriferous substances while 
the more toxic bacteria, that develop no telltale odor, con- 
tinue to grow and multiply, does not comply with the 
requirements demanded ,by a food preservative that asks 
for legal sanction. ... To retard the multiplication of 
the lactic acid bacillus, and thus prevent the souring of 
milk, while colon bacilli continue to multiply uninterrupt- 
edly is not the function of a true food preservative. . . . 
The man who adds formaldehyde to his milk takes down 
the danger signal, but does not remove the danger.' ' 

In regard to the action of preservatives on the digestive 
fluids, it should not be forgotten that preservatives if 
permitted in the food are liable to be taken by persons 
with every degree of digestive impairment. The free 
hydrochloric acid of the gastric juice will be neutralized 
by sodium sulfite, if this salt is used as a preservative, 
and this cannot fail to interfere seriously with the action 
of the digestive enzymes. It seems to be well established 
that formaldehyde also interferes with their action. In 
regard to some of the other preservatives, sufficient 
experiments have not been made to prove definitely that 
they interfere with the digestive functions. 

The author above quoted believes that a food preserva- 
tive in order to receive legal sanction should keep the food 
in a wholesome condition and not simply retain this 



360 SANITARY AND APPLIED CHEMISTRY 

appearance while bacterial changes continue ; in the largest 
quantities used it should not impair any of the digestive 
processes ; and finally this substance must not be a cell 
poison, or, if it is a cell poison, it must be added to foods 
only by persons who have special training, and not by a 
manufacturer who has no knowledge of the subject. 
Foods containing these preservative substances should 
also be plainly marked, so that the presence of the pre- 
servative can be known to the consumer. 

" If the use of any preservatives is to be permitted in 
food, boric acid and sodium benzoate are the least objec- 
tionable, since they appear to have less tendency to dis- 
turb the digestive functions than have the others." 1 

At the conclusion of an exhaustive series of experiments 
upon the effect of boric acid and borax on the general 
health, Dr. H. W. Wiley says : "It appears, therefore, 
that both boric acid and borax when continuously given in 
small doses for a long period, or when given in large 
quantities for a short period, create disturbance of appe- 
tite, of digestion, and of health." 2 

Some of the preservatives most used are borax (Na 2 B 4 7 , 
10H 2 O), boric acid (H3BO3), salicylic acid (HC 7 H 6 3 ), 
ammonium fluorid (NH 4 F), benzoic acid (HC 7 H 5 2 ), so- 
dium benzoate (NaC 7 H 6 2 ), formaldehyde (HCHO), so- 
dium sulfite (Na 2 S03) and sulfurous acid (H 2 S0 3 ), beta- 
naphthol (Ci H 7 OH), abrastol Ca(C 10 H 6 SO 3 OH) 2 , and 
saccharin (C 6 H 4 COS0 2 NH). The detection of small 
quantities of these substances in food usually requires 
the service of an experienced analyst. 

Borax and boric acid are often sold under various names, 

1 H. Leffman, Jour. Franklin Inst. 147 (2), 97-109. 

2 Circ. 15 or Bui. 84, U. S. Dept. Agric, Bu. Chem. See also "Food 
Inspection and Analysis," Leach, 3d ed., pp. 821-822. 



PRESERVATION OF FOOD 361 

such as " Preservaline," and mixtures of borax with other 
preservatives are also on the market under various trade 
names. This preservative is used especially in milk and 
meat products. The method of detection given under 
Milk, Experiment 166, should be followed. 

Salicylic acid is a white crystalline powder, very soluble 
in alcohol, and soluble in 500 parts of water. It is used 
in preserving fruit products, beer, cider, milk, etc. 

Experiment 190. To test for salicylic acid, to 50 cc. of 
the substance to be tested, made feebly acid with a few drops 
of sulfuric acid, add an equal bulk of a mixture of equal parts 
of ether and petroleum spirit, and shake vigorously. Allow 
the liquids to separate, and draw off the solvent, and allow it 
to evaporate at a gentle heat. If salicylic acid is present, 
fine silky crystals will usually be seen. Add to the residue left 
on evaporation a few drops of water and a drop of very dilute 
ferric chlorid or of ammonium ferric alum solution, and if there 
is any salicylic acid, a characteristic violet color is produced. 

Sodium benzoate, which is more frequently used as a 
preservative than benzoic acid, is a white granular powder, 
of a slightly aromatic odor, and disagreeable taste. It is 
readily soluble in water, and the solution is used as a 
preservative, especially for catsup, mince meat, jams, and 
jellies. 

Experiment 191. Benzoic acid or a benzoate may be de- 
tected in the absence of salicylic acid by Peter's method, 1 
which depends on oxidation of the benzoic acid to salicylic 
acid by treatment with sulfuric acid and barium peroxid, and 
then applying the ferric chlorid test for salicylic acid noted in 
Experiment 190. 

Sodium sulfite is a white solid readily soluble in water. 
It has the characteristic taste of the smoke of a burning 
sulfur match. 

1 Bui. 65, p. 160, U. S. Dept. Agric, Bu. Chem. 



362 SANITARY AND APPLIED CHEMISTRY 

The sulfites are used especially to preserve meat and 
meat products, and give them a " natural " red color, and 
for alcoholic beverages, cider, fruit juices, and catsup. 

Experiment 192. As the test for the detection of sulfu- 
rous acid depends on converting it into sulfuric acid, the fol- 
lowing method may be used : Place 200 g. of the suspected food, 
which, if solid, should be ground with water in a mortar, in a 
flask, make acid with phosphoric acid, connect with a condenser, 
and distill slowly, till 20 cc. have come over. Boil this distil- 
late in a large test tube or small flask with bromin water and 
add a few drops of barium chlorid. The formation of a white 
precipitate of barium sulfate indicates that a sulfite was present. 

Formaldehyde is a gas that readily dissolves in water. 
The 40% solution is usually sold under the name of "for- 
malin." The gas has a characteristic odor. It is used as a 
preservative for fish, broken eggs, meat products, milk, 
etc. The method of testing for formaldehyde is given 
under Milk, Experiment 167. 

Experiment 193. To some egg-white, in a porcelain evapo- 
rating dish, add a moderate quantity of formaldehyde. Place 
the dish over a water bath, and warm, not above 60° C, fonsome 
time. 

Saccharin acts slightly as a preservative, but more 
especially as a sweetening agent. It is a white crystalline 
powder, soluble in 1000 parts of cold water, and has about 
500 times the sweetening power of cane sugar. At present 
it is not extensively used, except in some cases in soft 
drinks. In many states its use is forbidden by law on the 
ground that it takes the place of sugar, which is a valuable 
nutrient and that it may have an injurious effect on the 
system if taken continuously. 

Experiment 194. For the detection of saccharin in jelly, 
preserves, or canned vegetables, use about 20 grams of the sam- 



PRESERVATION OF FOOD 363 

pie. Grind this in a mortar with about 40 cc. of water, strain 
through muslin, acidify with 2 cc. of dilute sulfuric acid, and 
shake moderately with ether. Separate the ethereal layer 
and allow this to evaporate spontaneously in a watch glass, 
and take up the residue with water. If saccharin is present, 
this solution will have a sweet taste. To confirm this test add 
one or two grams of sodium hydroxid, place the dish in an oil 
bath and heat to 250° C, for twenty minutes. This will con- 
vert the saccharin into salicylic acid. After cooling and acidify- 
ing with sulfuric acid, extract as usual and test for salicylic 
acid according to Experiment 190. 1 

COLORING OF FOOD PRODUCTS 

This is another method of falsifying food, and making 
it appear better than it is, or of simulating wholesome 
foods with a combination of entirely foreign substances. 
The coal-tar colors, of which there is an endless variety, 
lend themselves very readily to the coloring of foods and 
beverages. The use of these dyestuffs is not only liable 
to lead to injury of the health of the consumer from the 
poisonous nature of the coloring material, but the consumer 
is deceived so that he buys the goods thinking they are of 
greater value than they actually are. There are some of 
the coal-tar or aniline colors which are of themselves harm- 
less, but in the process of manufacture some poisonous 
substance such as arsenic or mercury is used, and a little 
of this remains in the finished product, making it dangerous 
for consumption. It is true that so far as we know the 
coal-tar colors are mostly harmless, so the chief cause for 
objection to their use is on account of the fraud on the 
consumer. The United States Department of Agriculture, 
after a careful examination, has approved of the use of eight 
aniline colors which are known as " certified dyes." These 

1 Bui. 65, p. 51, U. S. Dept. Agric, Bu. Chem. 



364 SANITARY AND APPLIED CHEMISTRY 

only should be used in foods. In some cases vegetable 
colors, such as turmeric, logwood, annatto, Brazil wood, 
beets, and safflower are used. The only animal coloring 
matter in common use is that of the cochineal, called 
carmine red. 

Experiment 195. Test a sample of tomato catsup for a 
coal-tar dye by the method described in Experiment 147. 

Salts of copper are sometimes used to impart an artifi- 
cial green color to canned goods, particularly peas, beans, 
brussels sprouts, and pickles. An old-fashioned method 
for greening pickles was to put a copper cent in the 
vinegar in which they were boiled. The practice of color- 
ing food material by the use of compounds of copper is 
more common on the Continent than in the United States. 
Imported goods frequently contain considerable copper. 1 
Examinations of a large number of canned vegetables 
greened by copper, as bought in Massachusetts, showed 
them to contain from a trace to 2.75 g. per can, calculated 
as copper sulfate. The author has found in an ordinary 
pickled cucumber the equivalent of one seventh of a grain 
of copper sulfate. 

Experiment 196. Incinerate fruit or vegetables in a por- 
celain evaporating dish with sulfuric acid, adding a little nitric 
acid from time to time until the carbon is completely consumed 
and a grayish or reddish ash is obtained. Add a few drops of 
hydrochloric acid to the ash, filter into a small test tube, and 
add to this solution an excess of ammonium hydroxid, when a 
blue color indicates the presence of copper. 

1 Leach, "Food Inspection and^Analysis," p. 909. 



CHAPTER XXVIII 
ECONOMY IN PREPARATION OF FOOD; DIETARIES 

The importance of cooking food has already been dis- 
cussed (p. 165). It is owing to the practice of cooking food 
that the dietary of civilized man has been greatly enlarged 
and improved. Many kinds of food which would be 
not only unpalatable, but indigestible, in the raw state are 
rendered wholesome and nourishing by some process of 
cooking. So the proper cooking of food may be regarded 
as an art; indeed, one distinction of a civilized man is 
that he is one who prepares his food by cooking. Most 
foods, with the exception of fruits, require cooking ; animal 
foods especially are cooked to make them palatable and 
wholesome. 

In addition to what has been said on previous pages 
about cooking in the case of individual foods, since all the 
different foods have now been studied, some general state- 
ments will be more readily understood. 

DIGESTION OF STARCH 

In the cooking of starchy foods it will be noticed that the 
starch grains, as " put up," so to speak, by nature, are very 
close and compact in most seeds, so that they will with- 
stand any natural temperature, and a moist as well as a 
dry climate. When these seeds are to be used for food, 
they must be soaked with water and allowed to swell. 

365 



366 SANITARY AND APPLIED CHEMISTRY 

By this treatment the fine particles of starchy substances 
will be in a much better condition to be attacked in the 
process of digestion by the alimentary liquids. The 
starch grains are rendered much more digestible by being 
cooked. The food should be thoroughly mixed with the 
saliva so that the ptyalin, the digestive ferment which it 
contains, may readily act on the starch, thus splitting it 
up into various dextrins and finally into maltose, the end 
product of its digestion. These changes, however, are only 
begun in the mouth, and take place best in an alkaline 
medium. 1 After about half an hour the acid fluids of the 
stomach tend to check the salivary digestion, and the 
food passes on into the duodenum before all the starches 
are changed to maltose. 

DIGESTION OF FATS 

Fats undergo a kind of combustion in the body and are 
changed to carbon dioxid and water, thus furnishing much 
of the heat needed by the body. If these are too expen- 
sive, their place may, to a considerable extent, be taken 
by the carbohydrates. In any case the excess, or that 
which remains over what is actually used up in doing the 
work required of the body, is stored up, and may be drawn 
upon as a reserve. Fats and oils are modified by digestion 
and prepared for absorption mostly in the intestines. 

The fats should be taken into the system as fats and 
not as products of the destruction of fats. In the process 
of digestion in tthe intestine, the fat is subjected to a 
double process of emulsification and saponification, which 
is brought about by the combined action of the bile and 
the pancreatic juice. This process is interfered with, 

1 "Food in Health and Disease," Davis, p. 29. 



ECONOMY IN PREPARATION OF FOOD 367 

and indigestion is produced when overheated fats are 
taken into the system. These volatile products which 
are produced by the decomposition of the fats cause the 
familiar irritation of the eyes, and a disagreeable odor, 
when food is fried. 

COOKING ALBUMINOUS FOOD 

In cooking an albuminous food, as an egg, if frying is the 
method of cooking used, the temperature is necessarily so 
high that the egg albumin becomes soluble with difficulty 
in the digestive fluids. Oysters, 1 when satisfactorily 
cooked, are heated only to boiling, or if fried, are sur- 
rounded by a batter, which protects the albuminous tissues 
from being overheated. A high temperature also greatly 
decreases the digestibility of the gluten of grains. It 
has been usually held that milk is less digestible if boiled 
than if simply pasteurized, but later authorities believe 
that the casein at least of the boiled milk is not less whole- 
some than that of raw milk. 

Beans and peas, which contain both legumin and starch, 
require considerable cooking to soften the cellulose and 
make the starch digestible. If these vegetables are cooked 
in hard water, there is danger that an insoluble compound 
shall be formed, by the combination of the legumin with 
lime or magnesia in the water; steaming, as previously 
suggested, will partly obviate this difficulty. 

COST OF FOODS 

Again, in seeking for economy of food, the question 
arises, What food furnishes the largest amount of nutri- 
ment at the most reasonable cost? As we shall see a 

1 Richards and Elliot, "The Chemistry of Cooking and Cleaning," 
p. 51. 



368 SANITARY AND APPLIED CHEMISTRY 

little later, the amount of energy in terms of " calories " 
that each food is capable of producing, has been carefully 
determined, and this will furnish a clew to the value of 
different foods. For instance, a certain sum invested in 
bread will yield much more energy than the same sum in- 
vested in milk or in meats. Both the latter foods are 
valuable, but they are not cheap. 

To build up the tissues, a cheap form of protein is that 
contained in peas or beans, while eggs are eight times as 
expensive, and beef five times as expensive at ordinary 
prices. 

VEGETABLE VERSUS ANIMAL FOOD . 

In general, vegetable food is cheaper than animal food, 
either as a source of energy or to build up the tissues. The 
reason for this is evident when we consider that the vegeta- 
ble foods are built up from the simple substances found in 
air, water, and soil, while the food of animals consists of 
highly organized vegetable or animal substances. One 
author states, as an illustration of the comparative cost 
of vegetable food, that 2\ acres devoted to raising mutton 
would support a man for a year, while the same amount 
devoted to the growing of wheat would support 16 men for 
the same time. It may be said that as the vegetable food 
is so much more bulky it would require much more heat 
to cook it, but with the best appliances, the cost of this 
additional fuel would not counterbalance the increased 
cost of animal food. 

While carbohydrates are cheap constituents of food, pro- 
teins and fats are expensive. If the fat is derived from 
animal sources, this is particularly true, but foods contain- 
ing cottonseed oil, and the oil of some varieties of nuts, 
furnish fats at a reasonable price. 



ECONOMY IN PREPARATION OF FOOD 369 

ECONOMY OF FOOD 

There is no necessary relation between the cost of a food 
and its nutritive value, for we pay for color, size, appear- 
ance, and flavor, in foods, not for their value in feeding the 
body. There is practically as much nourishment in the 
cut of beef costing 8 cents a pound as in that costing 16 
cents ; a fine quality of starch in the form of arrowroot 
or sago is expensive, but the same amount of starch of a 
different flavor made from corn is very cheap ; a Roquefort 
cheese costs perhaps 75 cents a pound, while a cheese just 
as good for food, but made in New York State, costs only 
25 cents. 

METHODS OF COOKING 

It is important that the right method of cooking should 
be selected for each food ; a method that shall develop the 
agreeable flavors and make the food as digestible as 
possible. A cheap cut of beef may be made appetizing 
and wholesome by careful and skillful cooking, and it is 
equally true that an expensive cut may be made tough and 
tasteless by the ignorant cook. It is easy to spoil good 
food, and render it unwholesome by cooking it in fat, or 
by too slow heating. Potatoes may be cooked until they 
are " mealy " and the separate starch grains glisten in 
the light, or they may be water-soaked and waxy, and 
consequently slow to digest. Little skill is required to 
prepare sour or heavy bread, overheated toast, tough beef- 
steak, or muddy coffee, but the raw material costs just as 
much as if the food product had been made wholesome 
and agreeable. 

ECONOMY OF FUEL 

Great economy of fuel can be secured by the use of the 
right kind of stove or range, and by utilizing such an 
2b 



370 SANITARY AND APPLIED CHEMISTRY 

appliance asa" steamer/' so that half a dozen dishes can 
be cooked at one time over the same fire. This latter 
vessel is especially economical when gas, either natural 
or artificial, or gasoline is used for fuel. When the 
water is once brought to a boiling temperature in the 
steamer, a very small flame will keep it boiling, and the 
contents of the vessel will not become appreciably hotter, 
nor will it cook much quicker, if it boils much more tumul- 
tuously. Boiling water means 100° C, and it does not get 
any hotter, except under pressure. This is a fact too 
often forgotten by the cook, who is anxious to " hurry the 
dinner." 

Another interesting application of science to the culinary 
art is the invention of the Aladdin oven, by Edward Atkin- 
son. 1 This oven consists of a metallic chamber surrounded 
by non-conducting material, and so arranged that it can be 
heated from below with a good kerosene lamp or Rochester 
burner. Almost any food may be cooked in this oven, 
and it is especially adapted to the preparation of soups 
and the cooking of vegetables. 

The latest advance in this line is the " fireless cooker," 
which is so well known that a description is unnecessary. 
This device also substitutes a low temperature continued 
for a long time for a high temperature acting only for a 
short time. It introduces a great opportunity to save 
fuel, especially in the cooking of cereals and stews. 

DIETARIES 

We have already discussed the two general classes of 
nutrients (p. 168) and to some extent the properties of 
each class. Most of our knowledge of the composition 

1 "The Right Application of Heat to the Conversion of Food Mate- 
rial," Proc. Am. Assoc, for Adv. Science, 1890. 



ECONOMY IN PREPARATION OF FOOD 371 

and nutritive value of food has been accumulated, in the 
United States and Europe, within the past fifty years. 
Although the analysis of milk was reported by Boussin- 
gault and Le Bel in 1831, * yet it was not until Liebig, Play- 
fair, Boeckman, and others, about the middle of the last 
century, devised new methods for the analysis of foods and 
feeding stuffs, that we began to have a definite knowledge 
of this important subject. 

COMPOSITION OF FOOD MATERIALS 

With the adoption of the so-called Weende method, pro- 
posed by Henneberg in 1864, new impetus was given to 
this branch of investigation, and numerous improvements 
have been made, till now chemists generally agree on the 
methods of analysis to be employed. American food 
products first began to be investigated in 1878-1881, by 
Professor At water, under the auspices of the United States 
Fish Commission, and these investigations have been 
carried on more recently by agricultural colleges, the 
experiment stations of the various states, and the Depart- 
ment of Agriculture of the Federal government. The 
latter department, at an expense of from $10,000 to $20,- 
000 per year, has extended these investigations on human 
nutrition, until at the present time we have very complete 
data upon this subject. 2 

HEAT UNITS 

We have already learned that the analysis of a food 
shows the per cent of water, proteins, fats, carbohydrates, 

1 Atwater, "Foods, Nutritive Value and Cost," Farmers' Bui. 
23, U. S. Dept. Agric. 

2 Atwater and Woods, "Chem. Comp. of Am. Food Materials," 
Bui. 28, U. S. Dept. Agric, Office of Exp. Stations. 



372 SANITARY AND APPLIED CHEMISTRY 

and mineral salts, which it contains, and each of these, 
with perhaps the exception of water, has its food value. 
In order to compare the different foods, and calculate the 
relative amount of energy that can be obtained from them, 
the ordinary method is to determine the " heat units/ ' or 
" calories, " that can be produced by the combustion, 
under standard conditions of a given amount of food. 
Although the results are not exactly the same when food is 
oxidized in the body to produce energy, as when it is 
burned in a calorimeter to produce heat, yet this method 
is convenient for classification and computation of the 
relative value of foods. 

FUEL VALUE 

A calorie l is the amount of heat that is required to raise 
the temperature of one kilogram of water from 0° to 1° C, 
or approximately the amount of heat that would be re- 
quired to raise one pound of water 4° F., and is equal to 
3084 foot-pounds. The " fuel value " means the total 
calories obtained by the combustion of any food substance 
within the body. Considering the ordinary food materials, 
the following estimate has been made from the average 
amount of heat and energy or the " fuel value " of each of 
the classes of nutrients : — 

One pound of protein gives 1860 calories 

One pound of fats gives 4220 calories 

One pound of carbohydrates gives .... 1860 calories 

From this it will be seen that a pound of protein of lean 
meat, for instance, is about equal to a pound of sugar or 

1 See "Foods, Nutritive Value and Cost," Atwater, also "Practical 
Dietetics," Thompson, also "Air, Water, and Food," Richards and 
Woodman, "Chemistry of Food and Nutrition," Sherman, and "Food 
in Health and Disease," Davis. 



ECONOMY IN PREPARATION OF FOOD 373 

starch, in yielding heat and mechanical energy, and that 
fats have a fuel value about two and a quarter times that 
of the carbohydrates or protein. 

From the analysis of foods, to which reference has been 
made, it is possible to calculate the fuel value of a given 
amount of any food or of the rations supplied to a club, 
family, or charitable institution. 

RESPIRATION CALORIMETER 

Experiments have also been carried on by W. 0. At- 
water, at Wesley an University, and later by C. F. Lang- 
worthy, of the Department of Agriculture at Washing- 
ton, in what is known as a u respiration calorimeter." 
In this apparatus, which is a small closed room, the experi- 
menter remains for several days, and all the food, air, and 
water used is weighed and passed in to him, and all the 
products given off from the body are also weighed and 
analyzed. A careful record is also taken of the tempera- 
ture, and if the experimenter w T orks to exercise his muscles, 
a record is made of the mechanical work accomplished. 
" The main value of the experiments so far conducted in 
this calorimeter consists in the actual demonstration 
that the law of conservation of energy operates within the 
body in precisely the same manner as it does outside." 
In man it was found that the measured energy of the food 
consumed by the subject within the calorimeter was within 
1 % of the calculated or theoretical energy. 

STANDARD DIETARIES 

Having a knowledge of the composition of food, and a 
method for finding its value as an energy producer, we 
are in a position to study the food of different individuals 



374 SANITARY AND APPLIED CHEMISTRY 

or classes of people, or to study dietaries. A dietary, 
then, would be a known amount of food of known composi- 
tion, per day per person, and a standard dietary would be 
such a combination of materials as furnishes a sufficient 
amount of each of the nutrient substances to fully sustain 
the body. Professor Voit of Munich was one of the first 
to prepare standard dietaries, and his work has been 
supplemented by a large amount of work in the United 
States, especially within the last twenty years. 

DIETARY STUDIES 

It has been recently pointed out that there are two 
methods of estimating dietaries. One method is by study- 
ing the food consumption of classes of people or individuals, 
when they have a free choice of food, or when they procure 
such food as their circumstances allow them to buy. The 
other method contemplates the feeding to classes of in- 
dividuals, or to selected persons, certain foods of known 
weight and composition, and studying the nitrogen balance, 
as it is called ; that is, the amount of nitrogen taken into 
the body, daily, in the food, and the amount excreted. 
If there is more nitrogen excreted from the body than taken 
in, the system is evidently not fully nourished. If there is 
a slight excess of nitrogen maintained, the food is suffi- 
cient for the amount of work done by the individual. 
An excess of nitrogenous material, or of fat, may be stored 
in the body for use in emergencies. 

Returning to the ordinary method of studying dietaries, 
some examples may be given of the results observed by 
different chemists : * — 

1 Chittenden, "Physiological Economy in Nutrition"; also At- 
water, loc. cit. See also "The Principles of Human Nutrition," Jordan. 



ECONOMY IN PREPARATION OF FOOD 

Per Day per Man 



375 









Carbo- 


Fuel 


Nutritive 








HYDRATES 


Value 


Ratio 




Lb. 


Lb. 


Lb. 


Calories 


lto 


Well-fed tailors, Eng- 












land, Playfair . . . 


.29 


.09 


1.16 


3055 


4.7 


Blacksmiths, • England, 












Playfair 


.39 


.16 


1.47 


4115 


4.7 


Well-fed mechanics, Mu- 












nich, Voit .... 


.34 


.12 


1.06 


3085 


4.0 


Brickmakers, Munich, 












diet mainly corn meal 












and cheese, Ranke . . 


.37 


.26 


1.49 


4540 


5.6 


Brickmakers, Massachu- 












setts, very severe work 


.40 


.81 


2.54 


8850 


11.0 


Professional men, Mid- 












dletown, Ct., Atwater 


.27 


.34 


1.08 


3925 


6.6 


University professors, 












Munich, light exercise, 












Ranke 


.22 


.22 


.53 


2325 


4.7 



In the above table the nutritive ratio, mentioned in 
the last column, is the ratio of the protein to the sum of all 
the other nutritive ingredients. The fuel value of the 
fats, as previously noted, is two and a quarter times 
that of the protein and carbohydrates, so in the calculation 
the quantity of fats is multiplied by two and one fourth, 
and the product is added to the carbohydrates. This 
sum divided by the weight of the protein gives the 
nutritive ratio. Thus, in the first dietary quoted, 
the ratio of protein to fats and carbohydrates is as 1 to 
4.7. 

Some standard dietaries have been compiled by At- 
water, and represent what is believed by the several 
authors to be the amount needed by persons with different 
degrees of labor. The amounts are expressed in grams 
per day per individual. 



376 



SANITARY AND APPLIED CHEMISTRY 







Pbotein 


Fats 


Carbohy- 
drates 


Total 


Fuel 

Value, or 

Calobies 


Children, 6 to 15 . . . 
Women, at moderate 

work, Voit .... 
Man, at moderate work, 

Voit 

Man, at hard work, Voit 
Hard labor, Playfair 
Man, at moderate work, 

Atwater 

Man, at hard work, 

Atwater 


75 

92 

118 
145 
185 

125 

150 


43 

44 

56 

100 

71 

125 

150 


325 

400 

500 
450 
568 

450 

500 


443 

536 

674 
695 
824 

700 

800 


2041 

2426 

3055 
3370 
3748 

3520 

4060 



Experiment 197. Study the food used by a family or club 
for a period of several weeks. Note the actual weight of all 
food purchased, the cost, and the number of individual meals 
taken. From the tables given by Atwater, compute the total 
amount of protein, fats, and carbohydrates consumed, and the 
amount per day per capita. By the use of the same tables 
estimate the " fuel value " of the food, and the nutritive ratio. 
Tabulate the results as in the table quoted from Mrs. Richards 
on page 378. 

The daily amount of solid food consumed by the adult 
male is 50 oz. to 60 oz., and the water used is about the 
same. In case of severe labor this amount of food would 
be increased to 75 oz., the addition being mostly in fats 
and carbohydrates. 1 The standard ratio for health, of 
protein to fuel ingredients, has been placed at 1 to 5.8 
by the Experiment Stations of the Department of Agricul- 
ture. 

According to the standard dietaries given, and many 
others that might be quoted, an average man doing 
light work would consume 116 g. of protein, with suffi- 
cient fat and carbohydrates, to give 3050 calories ; some 

1 Thompson, "Practical Dietetics," p. 20. 



ECONOMY IN PREPARATION OF FOOD 377 

authorities l would decrease this as low as 100 g. of pro- 
tein. This could be obtained from a great variety of diet, 
either largely vegetable, or with a moderate amount of 
animal food. 

From some experiments by Chittenden, 2 and others, 
upon several groups of persons, some of whom lived seden- 
tary lives, and others of whom were athletes and soldiers, 
it was shown that it was possible to maintain the nitrogen 
balance and remain in good health with considerably less 
food, especially of the protein class, than the accepted 
dietary standards would indicate. On a diet containing 
only 42 to 55 g. of protein, instead of 116 to 121, and 
enough carbohydrates and fats to make 1750 calories, 
instead of 3050, the men lived and carried on their daily 
work for several months. 

Computations of the diet of farmers show an interesting 
similarity of fuel values of food in different parts of the 
world. 3 

Farmers in Connecticut 3,410 Calories 

" Vermont 3,635 

" New York 3,785 

" Mexico 3,435 

" Italy 3,565 

" Finland 3,474 

Average 3,551 " 

The following ideal daily ration of solid food is given 
by Mrs. E. H. Richards : 4 — 

1 " Chemistry of Food and Nutrition," Sherman, p. 228 ; also " Prin- 
ciples of Human Nutrition," Jordan, p. 196. 

2 " Physiological Economy in Nutrition"; "Economy in Food," 
Century Magazine, Vol. 70, p. 859. 

3 " The Fundamental Basis of Nutrition," Lusk, p. 14. 

4 "Chem. Comp. of Am. Food Materials," Bui. 28, U. S. Dept. Agric, 
Office of Exp. Stations. Also see Farmers' Bui. 23, U. S. Dept. Agric, 
"Principles of Human Nutrition," Jordan, p. 351. 



378 



SANITARY AND APPLIED CHEMISTRY 



Material 


Amount 
Grams 


Proteins 


Fat 


Carbo- 
hydrates 


Calories 


Bread 

Meat 

Oysters .... 
Breakfast Cocoa 

Milk 

Broth ..... 

Sugar 

Butter .... 


453.6 

226.8 

226.8 

28.3 

113.4 

453.6 

28.3 

14.17 


31.75 
34.02 
12.52 
6.60 
3.63 
18.14 

.14 


2.26 
11.34 
2.04 
7.50 
4.42 
18.14 

12.27 


257.28 

9.60 

4.88 

90.72 

27.36 


1206.82 
243.72 

70.01 
135.42 

75.55 
316.21 
112.17 
118.62 


Total .... 




106.80 


57.97 


389.84 


2574.60 



Here the amount of protein is nearly 107 g. or about the 
average suggested by the best authorities. 

In studying dietaries, it is also a practical question to 
ascertain what the cost of food per day per man should be. 
The habits of people differ so widely, that while in some 
countries good and sufficient food can be obtained at 10 to 
15 cents per day per capita, in other localities as much as 
35 cents per day is needed to procure satisfactory food. 
The following summary l of cost of food in different locali- 
ties, and under varying conditions of life, and showing the 
amount of food wasted, is of interest : — 





Cost of Food 
Purchased 


Calories 


Calories 
Wasted 


Nutritive 
Ratio 


Teacher's family, Illinois . 

Professional men, Connect- 
icut 

Mechanics' Boarding Club, 
Illinois 

Mechanic's family, Indiana 

Mechanic's family, Ten- 
nessee 

Students' Club, Kansas 2 . 


Cents 

27 

25 

23 
26 

16 

18 


3975 

3530 

3720 
3840 

4435 
3437 


700 

100 

330 
555 

345 


1:6.9 

1:6.8 

1:6.1 
1:7.9 

1:8.1 
1:7.6 



i Bui. 91, U. S. Dept. of Agric, Bu. Chem., 1900. 
2 Trans. Kan. Acad, of Science, Vol. XIX. 



ECONOMY IN PKEPARATION OF FOOD 



379 



As some of these figures were obtained several years ago, 
they would not indicate the cost of living at the present 
time, as similar experiments have shown that it has in- 
creased, within a few years, from 30 % to 60 %. 

The waste of food referred to covers the necessary loss 
from skins, seeds, bones, etc. ; and evidently, from the 
great difference in different cases, it also covers a large 
amount of unnecessary waste. 

From statistics collected in this country, especially in 
Massachusetts, and in Europe, an idea can be obtained of 
the proportion of income that is ordinarily used for the 
purchase of food by families in different circumstances. 1 
These figures will not, however, apply at the present time 
with the high cost of living : — 



Income 



Per Cent 
expended 
for Food 



Germany 

Workingmen . . . . 
Middle class . . . . 
Well-to-do 

Great Britain 

Workingmen . . . . 

Massachusetts 

Workingmen . . . . 

Workingmen . . . . 

Workingmen . . . . 

Workingmen . . . . 

Workingmen . . . . 



Dollars 

225-300 

450-600 

750-1100 



500 



62 
55 
50 



51 



350-400 


64 


450-600 


63 


600-750 


60 


750-1200 


56 


)ove 1200 


51 



When the income is small, considerably more than one 
half is expended for actual food. This surely leaves a very 

1 Fanners' Bui. 23, U. S. Dept. Agric, 



380 SANITARY AND APPLIED CHEMISTRY 

small amount for rent, clothing, and the other necessaries 
of life. Since a sufficient quantity of wholesome food is 
of the utmost importance, the poor man is justified in 
expending more than half of his income to provide his 
family with that which they need to give them health and 
strength. It is unfortunately true, however, that even 
the most intelligent people know less of the source, uses, 
and actual value of their food for fulfilling its important 
purpose than they do of almost any of the other daily 
necessities. 

It is estimated that at least 10% of the income is 
squandered not only by the well-to-do, but frequently also 
by those who have a very small income and so can ill afford 
it, in expensive food material which affords little nutrition, 
in unsatisfactory methods of preparation, in selecting foods 
out of season, by throwing away much valuable food 
material, and by using badly constructed cooking ap- 
pliances. Much careful investigation is needed along 
these economic lines, and painstaking instruction will 
ultimately improve these conditions which are at present 
so much deplored. 



INDEX 



Absinthe, 342. 
Acetylene gas, 64. 
Acetylene, solubility of, 65. 
Acid, benzoic, in foods, 360. 

citric, 268. 

fruit, 227. 

in fruits, 329. 

lactic, 300. 

malic, in fruits, 266. 

oxalic, poisoning by, 156. 

salicylic, in foods, 360. 

sulfuric, poisoning by, 153. 

tartaric, in fruits, 26S. 

tartaric, manufacture, 268. 
Aconite poisoning, 159. 
Activated sludge process, 109. 
Activated sludge, utilization of, 110. 
Aerated bread, 203. 
Air, 1. 

a mixture, 5. 

ammonia in, 15. 

amount required, 48. 

argon in, 3. 

carbon dioxid in, 7, 10, 11, 12, 13. 

carbon monoxid in, 15. 

composition of, 4, 6. 

constituents of, table, 4. 

dry, as purifier, 143. 

dust in, 18, 19, 20, 21, 22. 

examination for dust, 19. 

experiments, 5. 

expired, 12. 

gas, 63. 

helium in, 4. 

history, 2. 

humidity, 7, 8, 9. 

hydrogen sulfid in, 16. 

microorganisms, 20. 

nitrogen in, 7. 



Air, of crowded rooms, 11, 46, 47. 

of public buildings, 49. 

of the ground, 24. 

of vaults, 25. 

oxygen in, 2, 5, 6. 

ozone in, 16, 17. 

pure, 49. 

rare gases in, 4. 

rebreathed, 47. 

stagnant, 48. 

testing, 52. 

vitiated, 6. 

weight, 1, 2. 
Aladdin oven, 370. 
Albuminates, 281. 
Albuminoids, 282. 
Albuminous food cooking, 367. 
Albuminous substances, function, 

282. 
Albumins, 281. 
Alcohol, amount yielded, 340. 

as food, 343, 344. 

making, 340. 

physiological action, 342. 

properties, 327. 

wood, 38. 

wood as poison, 159. 
Alcoholic beverages, 327. 

classified, 328. 

consumption, 327, 328. 
Alcoholic liquor, use in baking, 202. 
Algae as food, 261. 
Alkalies, poisoning by, 153. 
Alkaloids, 157. 

in beverages, 326. 
Almonds, 278. 

bitter, 278. 
Alum baking powder, 209. 
Alum in bread, 210, 227. 

tests for, 211. 
Amides, 282. 



381 



382 



INDEX 



Amido-acids, 282. 
Ammonia in air, 15. 

in water, 80, 81. 
Ammonium carbonate, use in bak- 
ing, 203. 
Amygdalin, 278. 
Angostura, 342. 
Aniline blue, 138. 
Animal food, 368. 

amount used, 284. 
Animal foods, use of, 280. 
Annatto in cheese, 305. 
Anthracite coal, 33. 
Antimony, poisoning by, 155. 
Antiseptics, 140. 
Apples, composition, 264. 

ripening, 264. 
Argand lamp, 68. 
Argol, 268. 
Argols from wine, 330. 

source, 205. 
Argon in air, 3. 
Aristotle's experiments, 1. 
Arrowroot, 188. 
Arsenic in wall paper, 23. 
Arsenic poisoning treatment, 155. 
Artesian water, 74. 
Artificial silks, 118. 
Ash in wood, 31. 
Asparagin, 282. 
Asparagus, 259. 
Atmosphere, 1. 
Atwater's experiments, 373. 



Babcock tester, 297. 

Bacteria, in sewage purincation,411. 

multiplication of, 142. 
Baking bread, methods, 219. 
Baking, conditions, 217. 

loss in, 218. 
Baking powder, 205. 

alum, 209. 

cream-of-tartar, 207. 

homemade, 212. 

manufacture, 206. 

phosphate, 208. 

strength, 206. 



Baking powder, valuation, 206. 
Baking soda, 203. 
Banana, composition, 192. 

digestion, 193. 

flour, 193. 
Bananas as food, comparison, 192. 

cost, 192. 

cultivation, 191. 

shipping, 192. 
Barley, composition and use, 183. 
Barometer, use, 2. 
Beans and peas, cooking, 367. 
Beef as food, 287, 288. 
Beef extracts, 287. 
Beer, 336. 

adulteration, 338. 

composition, 337. 

preservatives in, 338. 

small, 338. 
Beet sugar, 241. 
Beets, 258. 
Begasse, 238. 
Benedictine, 342. 
Benzoate of sodium, 361. 
Berries, composition, 265. 
Beta-naphthol in food, 360. 
Beverages, alcoholic, 327. 

alcoholic, consumption, 327, 328. 

non-alcoholic, 312. 

non-alcoholic, amount imported, 
312. 

non-alcoholic, per capita con- 
sumption, 312. 

stimulating, comparison, 325. 
Bituminous coal, 33. 
Blaugas, 64. 
Bleached flour, 228. 
Bleaching, 138. 

agents used, 138. 

powder as disinfectant, 148. 

powder for water purification, 96. 
Bluing, 136. 
Bock beer, 338. 
Body, composition of, 168. 
Bone-black filters, use, 245. 
Bone-black, revivifying, 245. 
Borax in food, 360. 

use in cleaning, 124. 
Bran, use of, 223. 



INDEX 



383 



Brandy, 340. 

Brass and copper cleaning, 127. 

Bread, 201. 

aerated, 203. 

alum in, 227. 

and milk, 223. 

bad, 225. 

brown, 225. 

composition of, 221, 222. 

copper sulfate in, 226. 

crumb and crust, 222. 

dark, 226. 

fermented, 213. 

fresh vs. stale, 220. 

graham, 202. 

making good, 217. 

methods of raising, 202. 

moldy, 225, 226. 

non-fermented, 201. 

nutritive value, 222. 

overfermentation, 225. 

salt-rising, 216. 

unleavened, 202. 

varieties, 223. 

white, 226. 

whole wheat, 202, 224. 
Breakfast foods, 230, 232. 
Briquettes, 34. 
British Thermal Unit, 27. 
Bunsen's experiments, 3. 
Burners and lamps, 67. 
Burners for gas, 36. 
Burning fluid for lighting, 58. 
Butter, 307. 

adulteration, 310. 

composition, 308. 

fat, amount in milk, 297. 

fat, composition, 296. 

process, 308. 

renovated, 308. 

ripening, 307. 
Butterine, 308, 309. 



Cabbage, 258. 
Cacao, growing seeds, 322. 
Cafe au lait, 320. 
Caffein, 323, 326. 



Caffein, in coffee, 319. 
Caffeol in coffee, 319. 
Calcium carbid, use of, 65. 
Calcium hypochlorite, in bleach- 
ing, 138. 

as disinfectant, 148. 
Calcium saccharate, 243. 
Calorie, 27. 
Calories, 372. 

Calorimeter, respiration, 373. 
Camphene for lighting, 58. 
Candle flame, 55. 
Candles, dipped, 58. 

history, 56. 

materials used, 57. 

molded, 58. 
Cane sugar, making, 238, 239. 
Cannel coal, 33. 
Canning, commercial process, 356. 

food, 355. 

methods used, 356. 

objections to, 357. 
Caramel, 247. 
Carbohydrate foods, 170. 
Carbohydrates, amount necessary, 

376. 
Carbolic acid as disinfectant, 145. 

poisoning, 159. 
Carbon dioxid in air, 7, 10, 11, 12, 
13. 

in closed rooms, 10, 11. 

in respired air, 46. 

qualitative determination, 12. 

quantitative determination, 13, 
14. 
Carbon monoxid as poison, 160. 

in air, 15. 
Carbon tetrachlorid, use in clean- 
ing, 125. 
Carbonation, 242. 
Carrots, 259. 
Casein of milk, 299. 
Cassava, 187. 
Cassia, 346. 
Castile soap, 131. 
Cavendish, experiments by, 2. 
Celery, 259. 
Cellulose, 171. 

digestion of, 171, 



384 



INDEX 



Centrifugals, 240. 
Certified dyes, 363. 
Chaptalising, 334. 
Charcoal as deodorizer, 143. 

making, 31, 32. 
Chartreuse, 342. 
Cheese adulteration, 307. 

as food, 306. 

Brie, 305. 

Camembert, 305. 

Cheddar, 305. 

composition, 306. 

Edam, 306. 

Gorgonzola, 305. 

Gruyere, 305. 

Limburger, 306. 

making, 305. 

Neufchatel, 305. 

Parmesan, 306. 

Roquefort, 306. 

Stilton, 305. 
Chemical precipitation of sewage, 

110. 
Chemical preservatives, 358. 
Chestnuts, 278. 
ChevreuTs experiments, 134. 
Chloral hydrate, 159. 
Chlorid of lime, early use as dis- 
infectant, 148. 
Chlorin in water, 82. 
Chloroform poisoning, 159. 
Chocolate, 321. 

bitter, 323. 

history, 321. 

nutritive value, 325. 

sweet, 324. 
Cholin, 282. 
Chondrin, 282. 
Cider, 335. 

adulteration, 335. 

alcohol in, 335. 
Cinnamon, 346. 
Cities supplied by rivers, 100. 

water supply of, 98. 
Citric acid in fruits, 268. 
City water supplies, 84. 
Cleaning, 123. 

powders, 123. 
Closed rooms, carbon dioxid in, 10. 



Cloves, 346. 

Coagulation and sedimentation, 92. 

Coal, 32, 33, 34. 

anthracite, 33. 

bituminous, 33. 

cannel, 33. 

lignite, 32. 

semianthracite, 33. 

semibituminous, 33. 
Coal oil, 59, 60, 61. 
Coals, analysis of, 34. 
Coal-tar colors, 363. 
Cocoa, 321. 

butter, 323. 

commercial preparations, 323. 

manufacture, 322. 

nibbs, 323. 

product, composition, 322. 

shells, 323. 

soluble, 324. 
Cocoanut, 278. 

oil, 275. 
Coffee, adulteration, 319. 

bad effect of boiling, 320. 

berry, curing, 318. 

berry, growing, 318. 

effect of, 325. 

history, 317. 

Java, 321. 

leaf tea, 317. 

making the beverage, 320. 

Mocha, 321. 

pulping, 318. 

raw and roasted, composition, 
319. 

Rio, 321. 

roasting, 318. 

substitutes, 320. 

tannin in, 320. 

varieties, 321. 
Coke, 34. 

petroleum, 34. 
Cola, 324. 

effect on system, 326. 
Collagen, 282. 
Combustibles, 26. 
Compound lard, 277. 
Condensed milk, 302, 303. 
Contents, ix. 



INDEX 



385 



Cooker, fireless, 370. 
Cooking foods, 165. 

fruits, 269. 

meat, 284, 285. 

methods, 369. 
Copper, as a poison, 154. 

in food, 364. 
Copper sulfate, as disinfectant, 146. 

in bread, 226. 
Cordials, 328, 342. 
Corn, 179. 

as food, 180. 

composition, 180. 

nutritive value, 180. 

pones, 202. 
Corrosive sublimate, use of, 150. 

use in wounds, 150. 
Corrosives, 153. 
Cost of food, 367. 
Cottolene, 277. 
Cotton, fire-proofing, 121. 

mercerized, 115. 

structure, 115. 
Cottonseed oil, 275. 
Cottosuet, 277. 
Crackers, 222. 
Cream of tartar, 268, 330. 

baking powder, 207. 

use in baking, 205. 
Creatin, 283. 

Cresols as disinfectants, 146. 
Crowd poisoning, 47. 
Crutcher, use of, 131. 
Curacoa, 342. 

D 

Defecation, 245. 
Deodorants, 140, 146. 
Dew point, 8. 
Dextrin, 195. 

properties, 196. 
Dextrose from starch, 199. 
Diet, change of, 164. 

of farmers, 377. 

mixed, 164. 
Dietaries, 365, 370. 

standard, 373. 

studies, 373, 376. 
Dietary, Chittenden, 377. 

2c 



Dietary, Richards, 378. 
Diffusion process, 241, 242. 
Digestion of fats, 366. 

of starch, 365. 
Disease germs, how destroyed, 147. 
Disinfectant, ideal, 142. 

standardizing, 151. 
Disinfectants, 140, 141. 

tests for, 141, 142. 

which destroy spores, 147. 
Disinfection, by carbolic acid, 145. 

by sulphur dioxid, 144. 

of sewage, 110. 

of water, 95. 
Distilled liquors, 339. 
Dough raising, 201. 
Draft avoided, 52. 
Dried eggs, 293. 
Dried milk, 303. 

Drinking water and disease, 84, 85. 
Dry air as purifier, 143. 
Dry earth as purifier, 143. 
Dust and tuberculosis, 21, 22. 
Dust, effects of, 21, 22. 

in air, 18, 19, 20, 21, 22. 

in city streets, 20. 
Dyes, certified, 363. 

E 

Economy of food, 369. 

fuel, 369. 
Economy in preparation of food, 

365. 
Egg, substitutes, 293. 

white, composition, 291. 

yolk, composition, 291. 
Eggs, annual production, 291. 

composition, 292. 

cooking, 293, 294. 

desiccated, 293. 

in the diet, 292. 

preservation, 292. 

use in baking, 202. 

weight, 291. 
Elastin, 282. 
Electric heating, 45. 
Electric lights, 69. 
Emulsion, 278. 



386 



INDEX 



Erbswurst, 191. 
Ergot in rye, 228. 
Essences, fruit, artificial, 273. 
Evaporated milk, 302, 303. 
Extracts, beef, 287. 
flavoring, 272. 



Fabrics, household cleaning, 125. 
Faraday and candle flame, 55. 
Fat, amount necessary, 376. 

in food products, 274, 275. 
Fats, digestion of, 366. 

edible, 274. 

for soap making, 130. 
Fehling's test, 199. 
Fermentation and decay, 355. 
Fermentation, causes affecting, 216. 

in bread, 218. 
Fibrin, 282. 
Filled cheese, 307. 
Filter beds, use of, 108. 
Filters for household use, 96. 
Filtration, intermittent, of sewage, 

107. 
Fire to destroy disease germs, 147. 
Fireless cooker, 370. 
Fireplace, use of, 39, 40. 
Fish, fat and lean, 288. 

food value, 288. 

water in, 289. 
Flash-point apparatus, 61. 
Flax structure, 116. 
Flour, adulteration, 226. 

analyses, 177, 178. 

bleached, 228. 

compound, 226. 

entire wheat, 224. 

germ, 224. 

grades compared, 179. 

graham, 224. 

patent, 224. 

wheat, 176, 177. 
Food, accessories, 345. 

albuminous, cooking, 367. 

amount per day, 375, 376. 

analysis, 170. 

animal, amount used, 284. 



Food, breakfast, composition, 232. 

breakfast, use of, 232. 

canning, 355. 

cost per capita, 378. 

defined, 161. 

economy of, 369. 

for infants and invalids, 229. 

material needed, 166. 

materials, composition, 371. 

per cent of income expended for, 
379. 

predigested, 231. 

preservation, 354. 

products, coloring, 363. 

waste, 379. 
Foods, animal, 280. 

breakfast, 230, 232. 

carbohydrate, 170. 

carbonaceous, 168. 

character of, 166. 

classification of, 168. 

cooking, 165. 

cost, 367. 

early use of, 163. 

economy and preparation, 365. 

indigestible, 166. 

nitrogenous, 168, 280. 

selection of, 165. 

starchy, 189. 

starchy, adulteration, 189. 

use of, 161. 

wholesome or poisonous, 163. 
Formaldehyde gas as disinfectant, 

149. 
Formaldehyde in food, 359, 362. 
Formalin, use of, 149. 
Franklin stove, 40. 
Fruit essences, 273. 

jelly, 266. 

juices and alcohol, 328. 

sirups, 272. 
Fruits, composition, 265. 

cooking, 269. 

ripening, 263. 

structure, 263. 

sugar and acid in, 329. 

taste of, 264. 
Fuel gas, 36. 

value, 372, 373. 



INDEX 



387 



Fuels, burning, 29. 

constituents, 26, 27. 

economy, 369. 

gases, 28. 

history, 26. 

liquid and solid, 27. 
Fungi as food, 261. 
Furfurol in liquors, 342. 
Furnace, air for use in, 42. 

hot air, 41, 42. 
Furnace air, moisture in, 42. 
Fusel oil, 340. 



Galileo, experiments, 1. 
Garbage, disposal of, 103. 

in refuse, 113. 
Gas, acetylene, 64. 

air, 63. 

as fuel, 35. 

burners, 36. 

by-products, 62. 

combustion of, 56. 

illuminating, history, 62. 

lights, incandescent, 68, 69. 

manufacture, 62. 

Pintsch, 64. 

sand, 36. 

water, 63. 
Gases, fuel, 28. 

illuminating, composition, 65. 

in air, 15. 

offensive, 25. 
Gasoline, 37, 38. 

vapor, 38. 
Gelatin, 282. 
Gin, 341. 
Ginger, 347. 
Glass cleaning, 125. 
Globulins, 281. 
Glucose, 251. 

as food, 253. 

commercial, 251, 252. 

composition, 252. 

healthfulness, 253. 

uses, 252. 
Gluten in wheat, 175. 
Glycerin, 133. 
Goiter and water supply, 78. 



Graham flour, 224. 
Granulated sugar, 247. 
Granulator, 246. 
Grape sugar, 251. 

making, 252. 
Grapes for wine, 330. 
Grates, open, 51. 
Grease, solvents for, 124, 126. 
Great Lakes as water supply, 99. 
Greens, 259. 
Ground air, 24. 
Ground water supplies, 101. 
Gums, 196. 



Hamburg cholera epidemic, 87, 88. 
Hard waters, 77, 78. 
Heat, effect on meat, 285. 

for disinfecting, 144. 

units, 371. 
Heating, by hot water, 43, 44. 

by steam, 43. 

electric, 45. 
Heating and ventilation, 39. 
Helium in air, 4. 
Honey, 255. 

adulteration, 256. 

composition, 255. 
Hot-air furnace, 41, 42. 
Hot-water heaters, 43, 44. 
Household purification of water, 96. 
Household waste disposal, 111. 
Humidity of air, 7, 8, 9. 
Hydrochloric acid, use in baking, 

204. 
Hydrocyanic acid, poisoning, 156. 
Hydrogen peroxide, as disinfectant, 
147. 

in air, 16. 

in bleaching, 138. 
Hydrogen sulfid in air, 16. 
Hydrolysis of starch, 199. 



Iceland moss, 261. 
Ideal ration, 377. 
Illuminating devices, early, 56. 
Illuminating gas, 62. 



388 



INDEX 



Imhof tank, use of, 108. 
Incandescent gas lights, 68, 69. 
Income squandered, 380. 

vs. food, 379. 
Indigo blue, 136. 
Infant's food, 229. 
Infants' foods, 223. 
Injurious traits, 23. 
Ink spots, removing, 127. 
Introduction, xxv. 
Inulin, 196. 
Invalid's food, 229. 
Invert sugar, 254. 
Irish moss, 261. 
Iron stains, removing, 127. 
Iron sulfate as disinfectant, 146. 



Jams and their adulteration, 270. 
Jellies and their adulteration, 270. 
Jelly, coal-tar dye in, 271. 
from fruit, 266. 



Kerosene, 38. 

fire test, 61. 

flash-point, 61. 

history, 59. 

purification, 60. 
Knowledge of food lacking, 380. 
Koumiss, 298. 
Kummel, 342. 



Lactometer, use, 296. 

Lactose, 250. 

Lager beer, 338. 

Lake water, 73. 

Lakes for public water supplies, 99. 

Lamps and burners, 67. 

Lard, 276. 

compound, 277. 

kettle rendered, 276. 

neutral, 276. 

refined, 276. 
Lausen epidemic, 88. 



Lavoisier's experiments, 2. 

Lead salts as poison, 154. 

Leather cleaning, 125. 

Leaven, use of, 215. 

Leaves and stalks as food, 258. 

Lecithin, 282. 

Legumes, composition, 190. 

digestion, 190. 

history, 189. 

use as food, 189, 191. 
Legumin, 190. 
Lemon extract, 273. 
Lettuce, 259. 
Levulose, 255. 
Lichens as food, 261. 
Light efficiencies, 70. 
Light-producing substances, 54. 
Light, sources of, 54. 
Lighting, 54. 

systems, 70. 
Lights, electric, 69. 
Lignite, 32. 
Linen, 116. 
Liqueurs, 342. 
Liquor, 328. 
Liquors, adulteration, 341. 

distilled, 328, 339. 

fermented, 328. 

malt, 328. 

M 

Macaroni, 233. 

composition, 233. 

nutritive value, 234. 
Mace, 347. 

Malic acid in fruits, 266. 
Malt, 336. 

liquors, composition, 337. 

manufacture, 336. 

pale, 336. 
Maltose, 250. 
Mantles, life of, 69. 
Maple sirup, adulteration, 243. 
Maple sugar, 243. 
Maraschino, 342. 
Marble cleaning, 125. 
Marc, 330. 
Margarin, 308. 
Mashing, 336. 



INDEX 



389 



Masse cuite, 240, 254. 
Matt, 317, 325. 
Meat, diseases, 289. 

effect of cooking, 284. 

extractives, 284. 

jerked, 355. 

nutritive value, 387. 

parasites in, 289. 

roasting, 286. 

smoked, 355. 

stewing, 286. 

structure, 283. 
Mechanical filtration, 92, 94. 
Mercerized cotton, 115. 
Mercuric chlorid as disinfectant, 

150. 
Mercury poisoning treatment, 155. 
Mercury salts as poisons, 155. 
Messina epidemic, 86. 
Methyl alcohol poisoning, 159. 
Microbe killer, 141. 
Milk, adulteration, 304. 

amount used, 295. 

ash, 301. 

casein in, 299. 

condensed, 302. 

dried, 303. 

evaporated, 302. 

fat, standard, 297. 

formaldehyde in, 304. 

modified, 250, 303. 

of various animals, composition, 
296. 

pasteurized, 301, 302. 

proteins, 300. 

sour, use in baking, 204. 

souring, 300. 

specific gravity, 296. 

sterilized, 301. 

sterilized, changes in, 301. 

structure, 295. 

sugar, 250, 300. 
Millet, 183. 

Milwaukee sewage system, 106. 
Mineral substances in water, 75. 
Mineral waters, 75. 
Modified milk, 303. 
Moisture, in air, 7, 8. 

in furnace air, 42. 



Molasses, 244. 
Morphine as poison, 157. 
Morphine poison treatment, 158. 
Moss, Iceland, 261. 

Irish, 261. 
Mucin, 282. 

Municipal refuse, 112, 113. 
Muscles, structure, 283. 
Mushrooms, 261. 

poison, 262. 
Must, 330. 
Mustard, adulteration, 348, 

black, 348. 

oil of, 348. 

white, 348. 
Myosin, 282, 283. 

N 

Natural gas, 35, 36. 
composition, 37. 

Nessler's solution, 83. 

Neutral, use in butterine, 309. 

Nitrates in water, 81. 

Nitrites in water, 81. 

Nitrogen balance, 377. 

Nitrogen in air, 7. 

Nitrogenous substances, classifica- 
tion, 281. 

Non-alcoholic beverages, 312. 

Nuclein, 282. 

Nutmeg, 347. 

Nutritive ratio, 375. 

Nuts, composition, and food value, 
277. 



Oatmeal, cooking, 182. 

use as food, 181. 
Oats, composition, 181. 
Odor killers, 144. 
Oil, cocoanut, 275. 

cottonseed, 275. 
Oil lamps, 58. 
Oils, edible, 274. 
Oleomargarin, making, 308. 

production, 310. 

tax, 309. 
Oleo-stearin, 309. 



390 



INDEX 



Onions, 260. 
Oven, brick, 219. 

temperature, 213. 
Oysters, 289. 

Oxalic acid, poisoning, 156. 
Oxygen in air, 6. 
Ozone, composition of, 17. 

history, 16. 

in air, 16, 17. 

test, 17. 



Paint removing, 126. 
Paraffin, 58, 60. 

removing, 126. 
Paraform for disinfecting, 149. 
Paraguay tea, 317. 
Parsnips, 257. 

Pascal, experiments on air, 2. 
Peanut, 279. 
Peas in the diet, 191. 
Peat, charcoal from, 32. 

occurrence, 32. 

water in, 32. 
Pectin, 266. 
Pepper, 347. 
Peptones, 282. 

in meat, 283. 
Perry, 336. % 
Petroleum coke, 34. 

distillates from, 60. 

distillation of, 59. 

pipe lines, 59. 
Phosphate baking powder, 208. 
Phosphorus poisoning, 157. 

treatment, 159. 
Pintsch gas, 64. 
Plantain meal, 193. 
Plaster of Paris in wines, 333. 
Plymouth, Pa., epidemic, 86. 
Poison, definition, 153. 
Poisoning, by alkali or acids, 153. 

arsenic, 155. 

mercury, 155. 

morphine, 157. 

phosphorus, 157. 

prussic acid, 156. 

strychnin, 158. 
Poisonous gases, 160. 



Poisons and their antidotes, 152. 
Poisons, chronic and acute, 153. 

instructions for treatment, 152. 

metallic, symptoms, 154. 
Pomace, 335. 

Potassium permanganate, 146. 
Potato, structure, 186. 

sweet, 187. 

waste, 186. 
Potatoes as food, 186, 187. 

composition, 185. 

history, 185. 

production, 185. 
Preface to First Edition, v. 
Preface to Fourth Edition, vii. 
Preservation of eggs, 292. 
Preservatives, chemical, 358. 

danger of, 358, 359. 
Pressure blowers for ventilation, 51. 
Priestley, experiments on air, 2. 
Proof spirit, 327. 
Protein, amount necessary, 376. 
Proteins, 281. 
Proteoses, 282. 

in meat, 283. 
Proximate principles, 168. 

substances, 169. 
Prussian blue, 137. 
Prussic acid poisoning, 156. 
Ptomaine poisoning, 160. 
Pulse, 189. 
Purification of water supplies, 90. 

Q 

Quick process vinegar, 349, 350. 
Quicklime for disinfection, 144. 

R 

Radiation, direct, 39. 

direct-indirect, 44. 

indirect, 41. 
Ramsay, experiments, 3. 
Ratafia, 342, 
Ration, ideal, 377. 
Rayleigh, experiments of, 3. 
Refuse, municipal, 112-113. 
Rennet, use, 299, 300, 305. 



INDEX 



391 



Renovated butter, 308. 
Reservoirs, water collected in, 98. 
Respiration, amount of air used, 46. 
Respiration calorimeter, 373. 
Rhubarb, 260. 
Rice, composition, 184. 

growing, 183. 

polishing, 184. 

production, 184. 
Ripening of fruits, 263. 
River water, 72. 
Rivers as water supplies, 100. 
Rochelle salt, 205. 
Roots as food, 257. 
Rum, 341. 

Rutherford, experiments on air, 2. 
Rye, composition, 182. 



Saccharin, 236. 

in food, 360, 362. 
Sago, 188. 
Sake, 338. 

Salicylic acid in food, 360, 361. 
Salt, composition, 353. 

manufacture, 352, 353. 

where found, 352. 
Salt-rising process, 215. 
Sand filtration, rapid, 92, 93, 94. 

slow, 92, 93. 
Saponification, 129. 
Sauerkraut, 259. 
Schonbein's experiments, 16. 
Scheele, 2. 

Scurvy in meat eaters, 289. 
Semianthracite coal, 33. 
Semibituminous coal, 33. 
Separator, use of, 298. 
Septic tank, use of, 108. 
Sewage, chemical precipitation, 110. 

composition, 104. 

definition, 104. 

disinfection^of, 110. 

disposal, 103, 105. 

disposal of, by dilution, 106. 

farming, 107. 

method of treatment, 105. 
Sewer gas, 25. 
Silk, cuprammonium, 119. 



Silk, structure, 118. 
Silks, artificial, 118. 

manufacture, 118. 
Silver cleaning, 127. 
Small beer, 308. 

Smell and taste, cultivation, 162. 
Soap boiling, 130. 

castile, 131. 

dried, 134. 

floating, 133. 

ingredients, 129. 

lime, 134. 

manufacture, 128, 129. 

mottled, 132. 

powders, 136. 

sand, 132. 

silicated, 132. « 

soft, 133. 

toilet, 132. 

transparent, 133. 

yellow, 131. 
Sodium benzoate, in food, 360, 361. 
Sodium bicarbonate in baking, 203. 
Sodium sulfite, 361. 
Softening water, 94. 
Soft soap, 133. 
Solids in milk, 299. 
Sorghum sugar, 244. 
Sour milk, 300. 
Spaghetti, 233. 
Spices, adulterants, 345. 
Spring water, 72. 
Stale bread, 220, 224. 
Standard dietaries, 376. 
Starch, chemical properties, 197. 

commercial, 193, 194. 

commercial sources, 174. 

cooking, 197. 

digestion, 365. 

grains, 197. 

hydrolysis, 199. 

methods of making, 193, 194. 

physical properties, 196. 

sources, 173, 174. 

with diastase, 200. 

with nitric acid, 200. 
Starchy foods, 189. 
Steam heat, 43. 

for destruction of germs, 147. 



392 



INDEX 



Steamer, use of, 370. 

Stearic acid, 57. 

Stimulating beverages, 325. 

Stove, heating by, 41. 

Stoves, ventilation with, 40, 41. 

Strychnin, poisoning by, 158. 

Sucrose, 237. 

Sugar, amount consumed, 249. 

as food, 235. 

classification, 236. 

commercial, 246. 

composition, 248. 

consumption, 236. 

cut or cube, 247. 

food value, 249. 

from beets, 241. 

granulated, 247. 

grape, 251. 

in fruits, 329. 

in grape juice, 330. 

invert, 254. 

loaf, 246. 

malt, 250. 

maple, 243. 

milk, 250. 

of milk, 300. 

powdered, 247. 

production, 241. 

properties of, 247. 

refining, 244. 

sorghum, 244. 
Sugar cane, 236. 
Sugar cane growing, 238. 
Sugars, classification, 235. 

history, 235. 

source, 237. 
Suint in wool, 117. 
Sulfur dioxid in bleaching, 139. 

for disinfection, 144. 
Sulfurous acid in food, 260. 
Sunlight as disinfectant, 143. 
Sweet chocolate, 324. 
Sweet potatoes, 187. 
Synthetic foods, 166. 



Tannin in coffee, 320. 
Tapioca, 187. 



Tapioca, preparation of, 188. 
Tartaric acid in fruits, 268. 
Taste and smell, cultivation of, 162. 
Taste, delicacy of, 162. 
Tea, adulteration, 314. 

effect of, 325. 

facing, 314. 

green and black, 313. 

growing and curing, 313. 

history, 313. 

lie, 315. 

making beverage, 316. 

Paraguay, 317. 

varieties, 315. 
Teas, composition, 315. 
Tees valley, epidemic, 86. 
Textile fibers compared, 119, 120. 
Textiles, 114. 

reactions with acids and alkalies, 
120, 121. 
Thein in tea, 316. 
Theobromine, 323, 326. 
Tomato catsup, 260. 
Tomato, history and composition, 

260. 
Torricelli's experiments, 1. 
Trades, injurious, 23. 
Triple-effect pans, 239. 
Truffles, 261. 

Tuberculosis and dust, 21, 22. 
Turnips, 258. 
Typhoid bacillus, 89. 
Typhoid fever and water supply, 86, 

87, 88. 
Tyrotoxicon in cheese, 307. 

U 

Ultramarine blue, 137. 



Vacuum cleaners, 22. 
Vacuum pan, 239. 
Vanilla extract, 272. 
Vegetable food, 368. 
Ventilating and heating, 39. 
Ventilating devices, 52. 
Ventilation, by gas jet, 51. 



INDEX 



393 



Ventilation, by exhaust fans, 50. 

by natural or forced draft, 50. 

by pressure blowers, 50. 

downwards or upwards, 50. 

importance of, 45, 46. 
Vermicelli, 233. 
Vermuth, 342. 
Vinegar, 348. 

chemical changes, 348, 349. 

cider, 350. 

eels in, 350. 

imitation, 351. 

making, 348. 

materials used, 349. 

quick process, 349, 350. 

strength, 351. 

use, 351. 

wine, 350. 
Viscose, 119. 
Vitiated air, 6. 

W 

Wall paper, arsenic in, 22, 23. 
Waste, household, 111. 
Water, ammonia in, 80, 81. 

artesian, 74. 

artificial purification, history of, 
91. 

boiling to purify, 96. 

boiling for disinfection, 148. 

carriage of sewage, 103. 

chlorin in, 82. 

cistern, 72. 

disinfection of, 95. 
Water gas, 63. 
Water, household, purification, 96. 

impurities in, 85. 

in wood, 30. 

mineral substances in, 75. 

municipal filtration, 92. 

natural purification, 90. 

nitrates in, 81. 

nitrites in, 81. 

of weUs, 73, 74. 

purification by iron, 97. 

sanitary analysis, 80. 

spring, 72. 

freezing for purification, 97. 



Water, organic matter in, 79. 
purified by oxidation, 90. 
river, 72. 
sources, 71. 
softening, 94. 
supplies, city, 84. 
supplies from rivers, 100. 
vapor in air, 7, 8, 9. 
Waters, hard, 77, 78. 
mineral, 75. 
permanently hard, 77. 
temporarily hard, 77. 
Well water, 73, 74. 
Welsbach system, 68. 
Wheat, analysis of, 176. 
composition, 175. 
hard and soft, 175. 
proteins in, 195. 
structure, 174. 
varieties, 176. 
Whisky, 341. 
Whole wheat bread, 224. 
Wine, aging, 331. 
composition, 332. 
making, 330. 
old, 331. 

pasteurization, 331. 
production, 334. 
storage of, 330. 
strength, 331. 
where grown, 339. 
Wines, adulteration, 333. 
classification, 332. 
dry, 333. 
fortified, 332. 
high, 340. 
plastering, 333. 
red and white, 332. 
still, 333. 
sweet, 332, 333. 
Wood alcohol, 38. 
Wood ashes, 31. 
as fuel, 29. 
kiln-dried, 30. 
water in, 30. 
Wool grease, 117. 
structure, 117. 
Workingmen, food of, 379. 
Wort, 337. 



394 



INDEX 



Xanthin, 283. 



Yeast, brewers', 214. 
cakes, 215. 



Yeast, compressed, 214. 
domestic, 214. 
use of, 213. 



Zinc salts as poison, 154. 



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TABLE OP CONTENTS 

Part I 

Food Values and Food Requirements. 

The Composition of Food Materials. 
The Functions of Food. 

Food as a Source of Energy. 

Food as Building Material. 

Food in the Regulation of Body Processes. 
Food Requirement. 

The Energy Requirement of Normal Adults. 

The Energy Requirement of Children. 

The Energy Requirement of the Aged. 

The Protein Requirement. 

The Fat and Carbohydrate Requirement. 

The Ash Requirement. 

Part II 
Problems in Dietary Calculations. 

Studies in Weight, Measure, and Cost of Some Common Food Materials. 

Relation between Percentage Composition and Weight. 

Calulation of the Fuel Value of a Single Food Material. 

Calculation of the Weight of a Standard or ioo-Calorie Portion. 

Food Value of a Combination of Food Materials. 

Distribution of Foodstuffs in a Standard Portion of a Single Food Material. 

Calculation of a Standard Portion of a Combination of Food Materials. 

Analysis of a Recipe. 

Modification of Cow's Milk to a Required Formula. 

Calculation of the Percentage Composition of a Food Mixture. 

The Calculation of a Complete Dietary. 

Scoring of the Dietary. 

Reference Tables. 

Refuse in Food Materials. 

Conversion Tables — Grams to Ounces. 

Conversion Tables — Ounces to Grams. 

Conversion Tables — Pounds to Grams. 

Food Values in Terms of Standard Units of Weight. 

Ash Constituents in Percentages of the Edible Portion. 

Ash Constituents in Standard or ioo-Calorie Portions. 

Appendix 
The Equipment of a Dietetics Laboratory, 



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